amazon has frankford arensenal tumblers for like 160 bucks i think. personally by the time i would have spent getting parts, paying for parts and the time spent putting it all together its faster and easier to drop 160 on the FA tumbler. but thats just me. and i got it for christmas lol.
For me the build process is part of the "fun"...not all my home made projects turn out but I find building, designing, troubleshooting and locating parts and materials is more gratifying than going online and buying it...youre right in that projects dont always end up being cheaper when you factor in time and materials and tools needed...but they usually are made more durable than mass produced items...for me personally, I own a garage full of tools, so that part of the process is taken care of..I also like to have the ability to customize something I've built to suit my needs..If I want to build a tumbler that will handle 30 lbs of brass I can and I know it will be built to handle it..
Like the post above me..I too have a lot of spare "parts" in my possesion and have a lot of friends with different backgrounds so always have access to different items and skillsets..we all help each other out with projects the same way we do with home repairs etc..part of a great community with similar interests