Here is what I did, possibly a little more expensive in the long run, but ......
Get a stripped lower, the lower is fairly easy to assemble just make sure to watch a few videos. Plus withj the right tricks you don't need special tools.
Get a basic complete upper that will meet your needs for a giving lenght of time (that time being when you can afford the additional parts you want).
Take the upper appart and put the new parts on, then get some additional parts and build another with the knowledge gain from taking the first appart.