What compressor are you going to use for this blasting? That's the expensive part of the operation, because you need a tremendous amount of dry air for the blasters to be effective. I do a bit of sandblasting, and its the same thing. I use a rented 70CFM compressor to run my blasting equipment.
As for the soda blaster, it all depends on how much you are going to do. The larger the tank, the more media it can hold, and the less frequently you have to stop, depressurize the tank, and refill. Go as big as you can afford/store. Whatever you do, get a spring-loaded deadman valve. I've seen what a runaway blasting nozzle can do, both to people and equipment.
:edit: After some reading, I've discovered something. Read this thread:
http://www.hotrodders.com/forum/soda-bl ... 28088.html
You ought to buy a good sandblasting rig, and convert it over for Soda. You can't pressurize the tank with soda, so they sell a conversion kit that will make a traditional sandblaster into a sodablaster.
Eastwood has a great reputation with those with more money than brains. Their prices are incredibly out of control, often for identical products that are available for a lot less. I'd avoid giving them a cent.
Example: Safety Wire Pliers.
Eastwood: $30, on sale for $20
http://www.eastwoodco.com/jump.jsp?item ... pe=PRODUCT
HF: $10
http://www.harborfreight.com/cpi/ctaf/d ... mber=45341
They are identical. I know because I bought one from Eastwood for use on one of our boats, and when it got here, it was the same darn thing I had from HF. Eastwood claimed it was a better unit. It was the exact same thing. I sent it back to Eastwood.
Eastwood doesn't MAKE anything, they just resell other people's stuff. I'm sure you can find the exact same blaster for sale through someone else for a lot less. Eastwood has a name, and a lot of Body Coddington-esque fools buy from them.