I too recommend 8 oz polyester from Dyson (or some of his heavier fabrics in polyester or nylon) and single part polyurethane.

Most oil-based polyurethanes will be a bit to very yellow/amber, however some water-based stuff is very pale in color or totally clear but reported problems have kept me away from most water-based finishes. Adding white tint will help, or you could use white enamel (although you won't get the translucent skin effect).

There's always a trade-off, and to keep costs low you just have to determine what characteristic you want most and let everything else fall where it may.

For sewing I like a heavier thread, I've been using upholstery tufting cord but braided polyester fishing line works well too. I don't much care for unwaxed floss, but it does get the job done. Really any thread or cord with 30 lbs breaking strength or greater will suffice.

If you end up going with the 8 oz. polyester from Dyson, just remember to sew it on relatively loose (don't pull so hard you open up holes at each stitch) and shrink it with a household iron set at about 350-360 deg. F.