I personally don't want to get into a screw on cap or partially disassembling the rifle to reload it, but I didn't want to spend $10K on a 50 BMG either, so this is what I came up with:
DA upper- $1800
ATRS lower $800
Magpul stock- $250?
Stock tube-$40
(prices approximate)
Originally I used a DA AR lower that I pulled off of one of my AR's, until the fall came and I wasn't using it much anymore so I sent it to ATRS.... Or- buying a separate AR lower is a less expensive route than the ATRS option, but it's restricted and also not as solid or streamlined. But if you have a spare AR lower or AR that you can steal the lower from, that's one way to put it together over time to spread out the cost if you want.

DA upper- $1800
ATRS lower $800
Magpul stock- $250?
Stock tube-$40
(prices approximate)
Originally I used a DA AR lower that I pulled off of one of my AR's, until the fall came and I wasn't using it much anymore so I sent it to ATRS.... Or- buying a separate AR lower is a less expensive route than the ATRS option, but it's restricted and also not as solid or streamlined. But if you have a spare AR lower or AR that you can steal the lower from, that's one way to put it together over time to spread out the cost if you want.