5V TTL interface GPSs can be had for about $10 on eBay. They are aimed at the RC market and although the GPS chip is a 3.3V chip, they have a 5V regulator on board and level shifters or 5V tolerant IO.
To use them with APRS you usually need to get RS232 output and to support the common 12V feed on the DE9 connector, the RS-232 / TTL adapter needs to incorporate a 12V/5V regulator.
This article describes a couple of modules that are available on eBay for a dollar or so, and suitable for modification by adding the regulator.
In the case of the lower module, a track has to be cut to disconnect the pad for 12V in from the existing circuitry.