I’ll echo Tim’s suggestion for using RTCM’s. You can use any of the other interfaces listed, but you will then need your node computer (Pi) at the same location where the repeater is. With the RTCM’s, it can be nearly anywhere and the same node can service both of your repeaters. Additionally, the RTCM’s can be configured to allow for local repeat functionality if for some reason your internet connection goes down. The other huge benefit of RTCM’s is doing multi-receiver voting.
I just purchased 3 new RTCM’s in the last month, so there is no issue getting them.
Here’s a link to info on the RTCM’s in the wiki: https://wiki.allstarlink.org/wiki/RTCM_Client