Have looked a bit more into the do it yourself soda blasting, previous thread here:
http://www.ausmini.com/forums/viewtopic.php?t=22868
Found a place that sells Sodium Bicarb after a bit of researching on the net, got a 25kg bag of it for $26.... can make a lot of banana cakes with that!!
I used a supercheap $15 sandblaster to do a bit of a test on one of the doors:
Took a few minutes to do this much. I think that the bicarb of soda is a bit too light compared to normal media that you would blast with. I seem to get a lot of dust happening with not the same amount of paint being removed comparatively. Although it is quite cheap and you can leave it on the grass and it won't kill anything (the neighbours may start wondering if you are cutting cocaine in your backyard though...)
Also made a home made sandblasting unit or more so "box", mainly because I was too cheap to buy a ready made one as I wasn't sure if my compressors were up to it.
Made it from a see through craft box (with wheels!!) and some pvc plumbing pipe from bunnings with some red rubber coated gloves. All up it might have costed about $15....
It does leek a bit of media though so have had to make a bit of a cheap seal with insulation tape and paper. Also one thing to be carefull of is cutting into the box as it breaks and cracks very easily - duct tape works well to fix that problem though
I found the Norton branded media you can buy in buckets from supercheap better than the soda here as the soda wasn't as abrasive.