good cheap primer for polyurethane-oil gloss paint

[pressuredrop]

after reading multiple positive reviews i am having a go at painting the exterior of my seawind with glidden floor and porch paint, a polyurethane oil gloss not unlike easypoxy or brightsides. price is about 1/4 of easypoxy...

i have done lots and lots of glass work and think it would be prudent to prime... however not looking to spend $80-100/gallon on easypoxy/brightsides primer... any recommendations for a "non marine" version of primer that will be compatible with the paint?

[Blue Stocking]

I feel your pain, having just spent $400 on Dupont epoxy primer. But is cheap primer worth the risk, after the hours and hours of your labor to get the hull looking good.