Full Spectrum does not have a good rep for tech support, so bear that in mind and research the support aspect if you think it will be important in sustaining your business.
If you make a living from your business, I'd consider one of the major brands, like Trotec, Epilog, or Universal Laser. Those are all well over your $5k target price though.
You might consider the Glowforge laser, but they've had a lot of warranty replacements and only offer support by email or their forum (no phone support) and an official response on either can take days to get and more days to finally resolve. To me, the Glowforge only makes sense for the casual hobbyist that doesn't need to worry about deadlines, warm temperatures (it shuts down above 75 °F), or need fast engrave speeds. The laser sold by Dremel might be better, but I've not seen much info on that. It's based on the Full Spectrum Muse, but supported by Dremel.
There are several import brands on the market. I have a Thunder Laser Nova 24, bought from a US reseller and it's given me no major problems. The US-based tech support has not been very good, though they do answer the phone (usually). Some folks like Rabbit Laser or Boss. If you haven't already done so, browse the engraving forum on SawMillCreek.org. There are lots of pro and serious hobbyist laser users there. Another source is the forum at RDWorksLab.com which focuses on lasers that have Ruida controllers and use RDWorks software. If you end up with a laser that uses a Ruida controller, consider buying the LightBurn control software ($80). IMHO, it's much better than RDWorks and offers some nice features.
BTW, are you in the US or elsewhere in the worls? That has a bearing on which brands might make sense for you.