The procon pumps can be sourced quite cheap if you look hard enough. It's the motors. The one posted in the link by reaper is actually very well priced IMO. As it's complete. A lot of coolers use pulse pumps. Which are prone to failure over time. My fronius is a pulse pump and I'll change it for a procon type when it fails as they are the best for the job.That would do but it's a bit pricey. I wonder if you could make a peristaltic pump and use that?
These have a mixed success rate. They only produce low psi but some people have got them to work.I've got a couple of central heating pumps but I think the high flow rate would make it somewhat ineffective.
The suggestion I made was a realistic one to your question. The most compact torch size you can go down to is a 9/20. By having a 9 your 200 amp machine becomes limited to around 120. Which as far as Alu is concerned is 3mm cold. By having a 20 you can use all 200 amps but it requires watercooling. Not complex at all and don't take hardly any space. If it's not an option for you then use a 17 (160 amps) about 4mm Alu from cold or stick with what you have. Was quite a realistic suggestion though. If you do want to try your hand at making a cooler let me know and I'll be happy to advise as I made one not too long ago.
Lol, yes, that's why I asked for advice on a suitable alternative. Just waiting on Jim to call me to sort the best one for my needs.Then you know the answer to your problem already.