Homebrew PCBs

I'm looking for a positive acting photoresist I can apply at home.
I've wanted to try Positiv 20 but can't seem to buy it in the USA. Can
it be had anywhere that you folks know of? Is it a decent resist?

What are you folks using? Yes, I know there are presensitized boards,
but they are very expensive.

Does anyone use dry film resist? I have a laminator, and wouldn't mind
using it if this type of resist works well. Does a regular laminator
work to apply this resist?

I've tried Datak negative acting resist, without much luck, and now my
bottle is so old, I don't trust it any more. Anyone use this stuff
successfully? I prefer pos resist because it's easier to print than
negatives.

How about radical ideas like Diazo compounds used for silk screening?
Would this stuff have fine enough detail and woul it stand up to
ferric chloride?

Any input would be greatly appreciated!