It really depends what kind of kits you're after. Cheaper stuff exists, like High Grade Gundams or 30 Minute Missions, and some of them are still pretty good when completed. Fancier stuff like the Berserk Fury there gets more expensive, of course.
If you just want something on the cheaper end to try out, I recommend a Spinatio or Entry Grade Gundam. Quick and easy build, no tools needed besides a nipper to cut the parts off the runners, and they're both good small-scale robot kits when completed.