1953mn, how much do you intend to blast?? IF your only doing one resto then I HIGHLY recommend having someone else do it.
I bought me a pressurized pot from Tractor Supply and have a 80 gal 7hp double stage compressor. Well, after spending $225 for the pot, buying the fine grade blasting sand (3.50 a 50lb bag) and the time I spent blasting it in the hot sun I learned my lesson.
For 150 bucks, probably 200 now, I could have had it down and moved on with my project. Noooo, had to do it my way. Unless you have a great air drying system plan on somedays doing nothing but uncloging the blaster!
I sold my blast pot for 100 bucks and vowed to never blast anything I can't get into my 46x26x26 skat blast cabinet. Now the cabinet is money well spent and I use it a lot.
As for media I'll throw in my .02. I have NO experience with Soda but I believe what Tim said, soda will NOT remove any rust. I say this because I HAVE some experience with the PLASTIC media and it will NOT remove ANY rust. Paint only. The plastic media would not remove even the light oxidation of rust from where I put my sweaty hand one day and it "rusted over". Plastic, and I believe soda, will remove paint and leave a smooth surface but if you want to get rid of ANY rust you will need sand.
I buy my sand from the local concrete mixing place and it comes in 3 sizes. Medium, Fine and extra fine. I have found that the Fine works for most stuff but since I can drop and change my sand easy with the cabinet I do keep a bag of Medium and Extra Fine under the cabinet..as well as a 50 lb suppy of glass beads.
Oh, I might add that "true" blasting sand is "sized" and will flow better than anything else. I'd stay away from river or play sand unless your running a pretty big hose and nozzle.
Hope my opinions help you in some way. Good luck, let us know what you decide...especially if you do it yourself!!