I installed 8Gb RAM in my NUC. I don’t think there is a huge difference between the price of a 4Gb or an 8Gb stick of 2400 RAM.
For your money, I think that I would be looking at a streaming setup that used either an SOTM or a Sonore microRendu or ultraRendu streaming device (separate power supply required) feeding into a DAC such as the Mytek Liberty or the Chord Qutest. There are a number of other DACs worth recommending (eg from Schiit or RME) but if you have a largish number of DSD files then Schiit and RME are probably out because I believe they don’t support DSD. You would have to use Roon to convert your DSD files on the fly to hi-res PCM in order to play them. You may or may not be happy with this.
I don’t live in the US, but I reckon you could get a Rendu (the microRendu and ultraRendu are both ‘Roon Ready’) with power supply along with either the Liberty or Qutest DACs for under $2,500, and you may not need to spend more. The Liberty supports both DSD and full MQA, but the Qutest just supports DSD. As I mentioned before, I wouldn’t restrict yourself to DACs that have inbuilt support for MQA. Although I like Tidal MQA Masters, I would personally be inclined to buy the best sounding DAC (irrespective of whether it supports MQA) and simply let Roon carry out the first unfold for any MQA files you may want to listen to. Remember most of the files you listen to will be PCM (either standard CD quality or hi-res) or DSD, so it’s more important to get a DAC that sounds good with these rather than one that caters for MQA. I suspect that you might prefer the Chord Qutest, but the only way to find out will be to listen to them.
If you can then arrange a demo of these DACs - they will sound ‘different’ and your opinion of their respective sound qualities may be different from mine.
By the way, the Sonore products support both Tidal and Qobuz.
One other thing that I would point out is that if Qobuz does become available in your area, Qobuz is likely to have a more comprehensive catalogue of ‘Classical’ and ‘Jazz’, whereas Tidal will probably have a more comprehensive catalogue of ‘Pop’ music.