I would like to be able to blast my own stuff and air tools seem to be a lot cheaper than buying individual corded tools. So, I would like suggestions on a cheap air compressor that would have the minimum specs for these tasks. I know tank size, PSI, and CFM are all factors, but don't know what would be required to do both blasting and use air tools.

I'll tell you what others will tell you. Get the biggest compressor you can afford - big as in tank size and actual motor size. While tank size is important, if the actual motor is relatively puny then you won't be able to realize all the advantages from having a larger tank.

Just to give you something to compare to, I paid ~$450 after tax at Lowes for this 26 gallon Campbell Hausfeld compressor. http://www.chpower.com/webapp/wcs/stores/servlet/chPrd3_10051_10001_93981_-1_10646_10692_

I can sand blast using a blasting tank without any problems. The compressor has to run the whole time, but it keeps up fine. I am not doing non-stop blasting so I am OK with that. But my compressor falls short when using certain air tools. In hindsight I should have gotten a bigger compressor, but I did not plan on doing the work I decided to do at the time I made my purchase.

As far as requirements to run different tools, the tool makers will state what PSI/CFM they need to operate, so that should give you a good idea. DA sanders take a lot of air to run, for instance. Even my little die grinders use up air pretty quickly.

If you do a search, you should find some good threads on this topic. :)

For sandblasting, you want lots of CFM. That means you want a 240v compressor. I'd look into a 5hp or 7.5hp (true HP) compressor. The 5hp will deliver around 18cfm. The 7.5hp will deliver around 30cfm. Either one should keep up really nice. Tank size doesn't really matter. Any 5hp or 7.5hp compressor will have an adequate tank for the compressor size.

I suppose a larger tank = motor runs less continuously, but I would agree that focusing more on the running HP of the motor is more important than tank size. They usually go hand in hand though.

If I ever have to get another one (which will happen) I am gonna save up for a rotary unit with an air cooler they are only about 5K

YOU CAN NEVER HAVE TOO MUCH AIR!

Brent

i have a 200psi 75 gallon air compressor from campbell hausfeld and it does pretty much everything i want but it falls short if i am using my plasma cutter or the 1 inch air gun but i like overkill

Its all about CFM not HP. I would recommend at least a 60 gallon tank that produces at least 13 CFM. Most likely to get that CFM, you are going to have an 80 gallon tank. Higher quality DA sanders have lower air consumption so you may be able to get away with continuous use. That being said, you could just put the extra money you would spend on the tools into the compressor and not worry about it.

#1 for 13+ CFM at 100 psi.

This is similar to the one I have: http://www.sears.com/shc/s/p_10153_12605_00918419000P?prdNo=7&blockNo=7&blockType=G7 I don't know how we worked with the old 20 gallon 4 cfm at 90 psi one after using the new one.

I purchased this compressor in 1997 and it still performs great. When blasting I have to stop for a few minutes to allow it to catch up, but for all the other work it is perfect.
I paid $398 for it and see them in stores for under $450 now.

http://i80.photobucket.com/albums/j199/64elcamino/tools/aircomp.jpg

+1 for CFM being very important for blasting.