You will get a smaller amber light in the dash panel, same one you see during lamp check. After you start it will flash for 75 seconds and go solid. In addition, every time you start the engine you will get a warning displayed in the EVIC and perhaps a single tone. You will have to press one of the buttons to clear it, but otherwise the EVIC display is the same.
A set of four new OEM TPMS sensor have been available on ebay for like $75. Thats what I put into my winter tire set. Search for part number 56029398AB to get OEMs. Folks used to have problems with non OEM sensors, dunno the current status.
Edit: Looks like about $50 for an entire set now. Tire shop will probably charge ~ $10 each to install the sensors when you have the tires mounted. So thats less than $100. I'm thinking $100 is not "high" cost, but you may have a different opinion.