OK. This makes more sense than a $15 polyurethane. Still, epoxy has tensile strength twice that of polyester, and compressive strength four times as great. It adheres better to the wood and is less brittle upon impact. Orthophthalic polyesters are even weaker than isophthalic resins also, though if it comes from a reputable marine supply house it may be suitable. You will also need some MEK peroxide catalyst, DMA, and perhaps some wax additive, as well as mixing containers, so there are some hidden costs.

If rock bottom cost is the objective, give it a try. Still, in my opinion epoxy is a much better bet for just a little more money. Here is a tip that might save you some money. I am in the epoxy floor business, and have built boats with leftover concrete coating and grouting materials. I have used Sika 35, Permagile Permatop Liquid Binder, and Neogard 70714/70715. My cost on these materials has been $34 - $42 per gal., and they have all worked just fine. They are all 100% solids, non-blushing and low-viscosity materials, and I suspect there are lots of others out there that would work just as well as the expensive marine resins. Truth be known, nearly all epoxies come from the same manufacturing sources, differing mostly in diluents and fillers.

Another tip: industrial painting and flooring contractors wind up with hundreds of gallons of leftovers from jobs. Our cost for disposing of these cats and dogs is $17 per gallon, so you may be able to call around and get a great deal on what is to them a storage and disposal problem! Good luck.