Here’s what I did:
$400 - Yaesu refurbished repeater DR1X from Yaesu you easily program via touchscreen and they ID
$100 - UHF mobile duplexer (notch filter) via eBay, some will tune it as well
$100 - UHF antenna I cut/tuned to my TX freq
$??? - LDF4-50A coax
Plus, some N patch cables between the repeater and duplexer, and another from the duplexer to the LDF4-50A coax as it is rather rigid. I also upgraded the repeater N panel connectors to silver.
When I first got things going I was using LMR-400 and a dual band antenna. Changing to the better coax and single band antenna I tuned for my TX freq made a big difference. Some fine people here on RR clued me in about the coaxial cable concern for repeaters. Another tool that helped me was an inexpensive VNA. I used it when cutting the antenna as well as fine tune the mobile duplexer. This system is used at my home location. At a high RF site I would use a BpBr (Bandpass/Band reject) duplexer.
Please note the Yaesu should be limited to 20W on UHF, but you could use an amplifier. While the Yaesu will deliver 50W, repeaters with a high duty cycle failed due to the heat. In a climate controlled environment, it may be fine at 50. Both I and a friend have ran ours at 50, but our duty cycle is low.