Tatsoul has carts with Envy needles installed
http://www.tatsoul.com/supplies/tatt...ges-c-274_678/

$19.99 for 10pcs tho? They look almost identical to the Elite membrane carts from NATS...

I have some Elites tucked away somewhere, I'm going to buy a box of rounds and mags from TS and do a comparison in the next couple weeks.