Thompson's water based waterseal.. but it doesn't look glossy. It has a flat finish. I have also used spray on polyurethane made for coating kid toys. It did not hold up well in the long run, though. The water seal has.
Yeah. If you look at alot of these paints some of them have 20-30 year garuntees. They may cost a little bit more but would be worth the money in the long run. You really will not need a lot so a little extra in price will not be that much anyway.