I am in the process of making wedding invitations for #2 son. I went to the dollar store and bought up all their stock of tape rollers for $1.99 each. I figured that would do it...nope. Each invitation consists of multiple layers and I was lucky if I got 25 of the first layer done....sure went through those tape rollers fast!
I had a coupon so I headed to my local Michael's store and picked up the pink roller from 3m. It took a learning curve until I got it down pat now. After a few mistakes on placement...I now hold it by the sides and eyeball it carefully to make sure all the edges are even. I then gently place down the top left corner and carefully place down the bottom left corner. If you don't press down hard right away the glue remains "stringy" and you can adjust the placement a bit.
As for the tape refills....I followed the links and the majority of the rolls only have 36 yards on them. The ones at Michael's have 72 yards. With the exchange, shipping and duty etc. it is cheaper in the long run to buy them at Michael's with a coupon. Also, my DH and I took a calculator and compared pricing to the smaller tape rollers. Just using the ones I purchased at the dollar store...the gun paid for itself a couple of times over.
BTW...I used the General Purpose tape and returned it for a refund. It may be a bit cheaper but I found the glue was really crappy and kept sticking to the tape roll and getting wasted. I prefer the Acid Free!