Agreed that the pumps are no good for H2O Cooling purposes
, but an alternative opinion on cost and what is needed....
As water cooling has gained popularity a lot more products have become available at decent prices...and with better performance too.
But a decent home MADE system can still be done for very little money.
It takes a LOT more work both in research and actually fabricating blocks and such, and performance IS likely to be behind what is available commercially now, but it can be done. And it can still be quiet and have pretty good performance, I expect....
Of course, I have not done it myself either...but the information is out there.......
Heater cores can be had for very little at junk yards- even if it takes you 2 or 3 to find one that can be used (no leaks), you may be able to have one for less than $10 (price from a junkyard near me that said I could have one for that. No promises.)
Blocks that are quite simple can still perform acceptably- anyone remember the "Pop Can Block" ? Admittedly, performance is not at the level of a White Water or RBX (or other top blocks) but it works.
There are very cheap pumps available that can suffice, and there are used ones sold for short money sometimes as well. There is also Ebay.
If you REALLY want water cooling and have a little - to - nothing budget I would say that it might be done for as little as $60, total.
Cheap vinyl tubing, cheap fans, cardboard shroud, junkyard heater core, used/cheap pump and a home made block.
Would this be a system that would compare well with one made from top commercial products?
Not performance-wise, probably.
But you could have one that cost much less, works and take even more satisfaction knowing that you MADE the thing, instead of just assembling it.