Please understand that this reply is just an old farts 2 cents worth, but as an "Old fart", I've got a half century of cents from which to reply.
One of the primary benifits, therefore objectives, of CNC is precision and accuracy. One of the primary drawbacks is how much it costs. Getting up and running is exciting, and we can't wait to see those motors spinning. The controller is the most expensive part of the machine, no matter how you look at it. As such, unlike guide rods, bearings, skate wheels, lead-screws, lead-nuts, gantry materials, et al, etc, it is the one thing that can not be inexpensively up-graded on down the road, after your project has taken it's first tenuous baby steps, and shown you that it indeed can make good use of a pair of quality athletic shoes. Swapping out all-thread for acme screw-stock, hardware store quality nuts for self compensatimg anti-backlash nuts, is not going to represent a big loss. Budget being tight, those are the places to scrimp now, if need be, upgrading later. Not so with the controller. Along with overall rigidity, lead-screws and lead-nuts, it's the most important part governing this acuracy and precision. Scrimp elsewhere if you must, but not here.
Now, I have absolutely NO asociation with Hobby CNC what so ever, but I must concurr that the Hobby CNC controller is the way to go. Get the biggest motors they have. The 3 Amp 305's. It's just not worth saving the 5 or 10 bucks not to. I can tell you from LOTTS of experience, they will go heads-up with most 400 Oz. motors, and many 500! They use all the power the board will output, and have very low inductance. That low inductance is where that power comes from.
I have been the proud owner of, well, up in the 3 digits, of HCNC controllers, so I like to feel like I've got some experience with them. By all means, if you can possibly afford it, go with the 4 axis PRO kit. I know, I know, money's tight, and that 4 axis is $20 more. If you ever have an axis go down, (it happens, usually due to a sloppy motor cable splice, faulty connector, piece of something getting into the enclosure causing a short), ESPEACIALLY if your machine is putting a little food on the table, or cranking out a piece for a cranky, client, a moment or two reconfiguring your software, and you're back in business, using that, "Spare", axis. That 20 bucks has paid for itself and then some. The PRO controller is so much better, in so many areas, there's not any point in going over it. That's why the AUPC's are discontinued. If you are concerned about power, get the PRO. If not, GET THE PRO. NOW,.........
Don't look at it as a board and motors, and that's what it costs. That's not reality. You don't know it, you can't see it, but take it from the many folks that have actually kept track of what it all finally added up to, and, well, most of them just finally QUIT adding it up to eliminate the shock. Yes, you've got that old tackle box, and you don't need fuses, and you can just pull the plug to turn it off, and that old parallel / centronics cable can be cut up and soldered in, and as long as you don't really put it in a real enclosure, that desk fan will blow it down cool enough and a wadd of tape will keep it up off the bottom of whatever, so it's not going to cost but a couple hundred bucks. That old PC's got a good power supply to modify, and you'll STILL end up with a couple hundred bucks in it, if it works, at least for a while.
I have shopped, and shopped , and shopped, and you can not beat the Hobby CNC "Package". If you're going to bild your own controller, and you're not going to be penny wise and pound foolish, get the "Package", get the 4 axis package, and get the 3, amp, 305 motors. The package contains virtually EVERYTHING but a transformer, (20 bucks), and an enclosure. (the modified PC power supply's no longer even recommended), Period. That's it. And that's everything to build a VERY NICE, TIP-TOP, CONTROLLER! Even buying in bulk, and I mean bulk, (I'm sitting across from 3,500 Ft. of the recommended 6 conductor motor cable), I could not do better. You buy, (in my oppinion), THEE best controller in this class, Thee most powerfull unipolar wired motors in this class, and everything else for just about gratis. All the power supply parts, fan, (24 volt fans aren't near as redilly available or cheap as 12 volt), guard, motor cables, fuse holders, switch, new parallel cable, power cable, heat-sink, heat-shrink, connectors, big handful of hardware, and on, and on, even self stick lables. EVERYTHING! OK. Just about done. One more plug. I also have absolutely nothing to do with Pactec. I've heard people say that's too expensive. I've never found a suitable enclosure for even $5 less. Now, "I'ts plastic!", they cry. OK. They're right. But,......I've shipped controllers the world over, and back when you still could, used "USPS Economy Surface", shipping. (had one box take 3 months to reach a coastal village in OZ). I had one take such a hard hit that it drove a motpor shaft into the side of another motor to the point that it looked like somebody took a 1/4" punch anf hit it with a 16 Oz. hammer. Ruined the motor, but the controller worked perfectlty, ( I DO pack very well), and there was not a single little flaw in the Pactec case. And that's with 6 pounds of transformer bolted to the bottom of it. AND, no matter what you use, you're going to have to locate and drill / cut ALLOT of mounting, vent, and fan holes. The HCNC package, includes with their most excellent instructions and wiring diagrams, FULL SIZED TEMPLATES, for all the case machining! Being an old tool and die dude, I've now made hard tooling to make all the holes, and can do 100 an hour, but before that, those templates were worth their weight in gold! OK. I honestly think that you can not do it cheaper. I KNOW that, for the money, you can't do it better! That's my 2 cents worth, and my 2 fingers are plum tuckered out! Thanks for listening, and,.........................................
ALL THE BEST!