Advice on Rackmount Ubuntu Server

This will be my first server build. I have been running Ubuntu server on an old second hand desktop for about 3 years now. I run all my services other than Nginx in docker. I would like to be able to do hardware trans-coding (do not have 4k files) running Jellyfin. I also run about 10 other containers. The box will only be accessible on my network so I cannot see more than 2-4 streams at once. I would also like to have a sfp nic. My budget is preferably below 600 but I could go up to 1k. I see documented builds I could copy but thought I would ask here. Thanks!