Hi Ame,
Sounds like you are a good candidate for a re-fill ink cartridge system or a bulk ink system. Here's a thread for you on re-fill carts, and some good suppliers for that... the supplier may also carry bulk systems.. check it out...
Durabrite vs. Inksupply.com HT ink -- Durabrite, You're Fired!
As far as what ink can you use with
JPSS, of course you can use pigment, but here's a thread where folks are testing other kinds of ink with success...
https://www.t-shirtforums.com/heat-p...tml#post268154
Good luck to you!