So I did some digging. 0.150mm seems to be the average thickness printers are using. But that size is hard to find in bulk. I was able to find 0.127mm though and should be fine. You may need to calibrate your exposure times with it though. The thinner film will have less light resistance than a thicker film so it'll cure resin a little faster. They have it in a large and small roll. Here is the larger rolls link. https://www.amazon.com/dp/B00U34WNOY/ref=cm_sw_r_cp_awdb_imm_0Q8575TYZMS76GBMB8P8 I haven't used this yet so I make no claims but it's got good reviews from 3d printers.

I'd recommend looking outside of Amazon and trying Google. I found some things on aliexpress as well. Just again be sure that you get an appropriate thickness. 0.050 is probably going to be too thin for example, and going above 0.200 is probably risking getting too thick.

Search around and crunch some numbers for size vs price. And determine how many vat refills you can cut out of that size.