Hi AylaStar13! Welcome to the forum
I see there may be a bit of confusion here, judging from the previous responses. What is sounds like to me, is that you are using a V2cigs ecig kit from v2cigs.com, not a modified ecig (mod) called V2. There is a mod called the Roughstack V2 that may be what the previous posters were referring to.
For the V2cigs, you can use any KR808D-1 cartomizers. Now, the blank cartomizers that are sold by V2cigs are really quite good by most accounts, they have a decent poly filler and produce very good vapor, a 5 pack is $8.95. Another good cartomizer is the Kanger KR808D-1 Horizontal Coil, available here
KR808D-1 Horizontal Coil Cartomizers by Kanger (5pc Empty) - Evcigarettes.com The price is the same as the V2cigs cartos, so this is where personal preference comes into play, give them a try and you might like them better. <edit> yes there is a bulk discount here, but after selecting the color they are out of stock in both black and white... sorry
As for a good replacement juice for the V2cigs Red flavor... I have not found one that is like the V2 Red I'm afraid, perhaps someone else viewing this thread may be able to provide a good equivalent? What I did find is that there are a LOT of juices I like much better than the V2Red flavor! Actually my first juice order was the tobacco sampler pack from Copper Creek
Welcome to Copper Creek - Online Store the House Blend was the winner of ECF's juice of the year 2011 and while to me, it is nothing like the V2 Red, it is absolutely delicious and I found I liked it much better than the V2 Red. I highly recommend it!
Hope this helps a little

Good luck!