You had posted a could be real complicated question and, therefore, only potential and approximate answer. Here is the link to the Cost of Living Comparison Calculator offered by Bankrate.com. It is not specifically for apartment living, however, I believe you can use this tool to approximately comparing the two locations on their cost of living. I am to recommend that you select FROM: SAN ANTONIO TX METRO - SAN ANTONIO TX (closest to Boerne) and TO: AUSTIN ROUND ROCK TX METRO - SAN MARCOS TX (closest to Wimberley and Canyon Lake) and click on "REFRESH LISTING" to see how they calculate. Here is the link:
Wish you had fun and good luck to find your answer. I hope this link helps and if you find a better answer, please share.
Judy Carey, Owner/Realtor
AmanVerde Real Estate
Daybreak RE, Broker