You get what you pay for.
If the above is what you really want, you already mentioned RME and you already stated "seems like the best option".
Well, what do you wait for then?
You want cheaper but same quality? Ain't gonna happen.
Yeah I agree with you, you get what you pay for.
But the main question for me is: With what % of the "main thing" are you satisficed with?? For example: My bass is 5 string Sterling by Music Man. Of course its not THE Music Man but its like 90% of the original quality and I paid 1/4 of the Music Man price. I'm not gonna pay 1k euros for the RME when I can get the same function (SPDIF) from a ~250e Focusrite. Especially since I'm only going to be recording for my soul.
Don't get me wrong, if I was rich I would go for the best stuff for sure Alas, I live in a 3rd world country and have a family to support.