I've tried the wader-inflation thing with a vaccum output and it works great. I filled the tub partway with soapy water then got the leaks with aquaseal.
1) Only buy neoprene waders that are double-seam sealed inside and out. If you save the money to get one-sided seam seal waders you will have leaks, period.
2) If it's cold enough for neoprene, consider OS Systems waders with fleece pants under. Won't leak at the seams. If you puncture it you can slap a square of duck tape on the inside and fish for the week. $150 / with good warranty