I went to the Form Labs website and it says that several resins (it was not specific) started as low as $35 a Liter.
Form Labs SLA resins cure at 405nm, and most other manufacture's resins are engineered to cure between 365 and 405nm, soooo...I would think that they'd work...but, I'm not an expert on Form Labs SLA printers, so I could definitely be wrong.
The Anycubic resin I use is priced at an msrp of $38.99/KG, but is on sale now at $26.99/KG. However, when I buy it, I purchase 10 liters at a time, which brings the price down to $15.89/KG.
Anycubic has other price breaks for lesser amounts, and maybe Form Labs has something similar.
Also, looking at their selection of resins, it appears that a lot of it is designed for dental and medical applications. I would think that type of resin is probably way expensive, and unless you're going to experiment with medical applications, a more general purpose resin would most likely be markedly less expensive.
That's my two bits worth!
Cheerio!
Bob Gilmore