well custom really does mean custom. its your personal taste and i have seen people built water cooling loops very cheaply.
to cool your ram with water cooling? never heard of it, that usually means you would have to go a very long way to make that happen
(it really is not needed)
you can get waterblocks for GPU's for around $100-$200 really depends on your locale.
not sure why you would need to watercool your GPU, unless you really need it.
i would suggest to you using a closed loop solution, personally recomend a h100i or even 2, (1 for your gpu if you must)
hope this helps.