Oversize 292 pistons shouldn't cost a whole lot different than standard 292 pistons. The cost to bore the 272 may offset any difference in the price of the pistons. Usually, the machine shops price to overbore is up to .060 over and anything larger costs extra.
I haven't looked recently but if anything I'd expect oversize pistons to be cheaper. When your only option is used blocks, how often can a standard size still be used? Not often. An oversize? Very often. Higher supply... but also higher demand, I would think.
Lawrenceville, GA