Rocketry is extremely cheap compared to some of the other hobbies I have had. I have probably only spent about $2000 since I got back into the hobby 3 years ago, which includes kits, parts, launch equipment, engines, finishing supplies, etc.
Compared to things like cars, photography, computer and technology equipment, rockets are still a relatively cheap investment. I will agree engines seem more expensive, but I always try to build my rockets to accept the engines offered at Hobby Lobby...where I can use that 40% off coupon to get engines to less than $2.00 per engine.
Of course, it helps that I cleaned out all the Boy Scout stores in San Antonio and Houston, plus the website when they were clearing out all their bulk packs. Engines were REALLY cheap with those sales...
FC