Those Kotobukiya kits can get pretty expensive, not that Bandai kits are all a super value. While I certainly have shelled out on kits $150+, most High Grade (smaller and simpler) kits are around $20-25, and Master Grade (larger and more intricate) kits are around $50-80. That's not even getting into things like tools and paint, like you mentioned. Gaming used to be my main hobby before I got into Gunpla, and that's cheap by comparison, even when taking a fancy gaming rig into account. Like any other hobby, though, you can do it on the cheap (simpler kits and basic tools) or dive into the deep end.
I know you said this isn't your hobby, but Bandai makes Entry Grade kits that are pretty inexpensive and simple to put together, no tools required even.
Thanks for the feedback! I'll see about writing something up.