What's the best I can buy?

[mbirand]

The Tambaqui might be nicer to the look and touch. Other than this I see no difference. Chose a streamer from the list "blue zone" that both suits your taste and pocket and you're "more than done".

are there any with onboard memory for local files or better yet with SDcard (sorry if this is being too ignorant)

 

[Nutul]

are there any with onboard memory for local files or better yet with SDcard (sorry if this is being too ignorant)

You might search... but I'd rather use their ability to use external USB SSDs, and/or connect to SMB/NFS shares and/or NASs and/or being LMS/Roon endpoints...
(Actually I'd rather leave Roon out of the equation - too expensive and wants you forever online even to play your local music...)

 

[KMSA]

I would look for an RME ADI-2 DAC.

I have one and I am very happy with it.

 

[rarewolf]

You might search... but I'd rather use their ability to use external USB SSDs, and/or connect to SMB/NFS shares and/or NASs and/or being LMS/Roon endpoints...
…

If the OP does have a local library, he might look at JRiver’s Media Center, which includes its media server, and is less expensive than Roon. Or, if he believes he’ll primarily be using a streaming service, either will require a streamer.

My smartphone works as a decent streamer (USB to Topping stack), but it took some research to get the same sound quality from my WiiM (via SPDIF) as from my smartphone (via USB). I might suggest a fully integrated streamer like one of the Eversolos, or one of the FiiOs

Cheers!