Lots of possibilities why you are getting such a variation in pricing. Is it just the programing that is your concern or is it the overall cost of having the part(s) made?
Some information that I think would help would be:
A drawing or picture of the part(s).
Any critical tolerances.
Order quanity and expected delivery time.
Not sure who is giving you the higher prices, but.
The simplest reason I can think of is a 3 axis shop will have programming for fixturing AND machining with possibly several operations.
The 5 axis shops may say its an "easy" part, but the time it takes to setup those types of machines can be considerably more costly. Also, if the quantities are not high enough, they "could" be pricing like a short run or prototype.
Hope that helps some.