Good source for MKIII and MKIV bits in USA?

[Marshal Mittens]

I would like to buy MKIII and MKIV bolters and arms for some conversions for my upcoming 30k army, but most bit stores charge half as much as the cost of an entire box of marines for 10 bolters and arms. Anyonw know a reasonable bits store in the USA or cheap shipping to the USA? Willing to consider resin alternatives as well.

[OttoVonAwesome]

I bought a 3-d printer for this reason and it's already paid for itself twice over.

[betrayer41]

Seconded on the 3d printer. Pats for itself in a month