Cheap canvas pads is what I have been using for studies and practice as I have been learning. The Strathmore canvas pads are pre-primed and I think would work great for your purposes.
Amazon Link: https://www.amazon.com/Strathmore-Canvas-Glue-Bound-Sheets/dp/B000KNNVJY?ref_=w_bl_hsx_s_off_web_2601417011
You aren't annoying me at all! Acrylic doesn't work the best on paper, but if you use mixed media paper or even better canvas paper it would be best. I found this - I can't tell if it's preprimed, but an extra coat of gesso wouldn't hurt.
Thank you! I've done a few on canvas pads like this https://www.amazon.com/Fredrix-3501-Canvas-Pads-16-Inch/dp/B000YQGG3A
But this was my first on a stretched canvas. Also I won't be selling this one... (it was my Christmas gift to my mom!) Hopefully I can paint some that will sell in the near future though!
correction: they're factory gessoed sheets sold as a pad. Its not raw canvas, and its archival.. I'd never trust factory gesso on a painting that I planned to build-up a lot of thick paint, but it works for little 1-3 hour paintings like this. http://www.amazon.com/Fredrix-3503-Canvas-Pads-24-Inch/dp/B0027ACEL4
Back when I had warehouse space, I used to make my own large batch oil-primed panels. These days my studio is confined to a couple hundred square feet. I experimented with several types of canvas pads and these by fredrix suite me the best. I prefer a slick surface with very little absorption. I usually can wait until a sell, and use my instructor discount to buy them in bulk for a slight discount, but still they're a bit pricey. Any suggestions of cheaper alternatives?
These were on sale for 190 a few weeks ago, so I picked one up for my girlfriend. They're a heck of a lot of fun: http://www.amazon.ca/Liquid-Shredder-70-FSE-Surfboard/dp/B00554USGM/ref=sr_1_5?ie=UTF8&qid=1433439532&sr=8-5&keywords=liquid+shredder