Tips for buying used receiver for a budget HT setup?

I want to convert my 2.1 setup to surround sound, at this point I’m aiming for 4.1, reason being is that I already have an extra pair of speakers.
The current set up is as follows;
Topping MX3 amp
Klipsch R-14M front speakers
Polk PSW10 sub
I also have a pair of Sony SS-B1000 speakers that I intend to use for the surround channels
All I really need at this point is to replace my mx3 with a surround receiver to add those sony’s in.

My main limitations are that I want it’s dac to be at least as good as I currently have in the MX3 and amp to be more powerful, and ideally retain some of the functionality of the MX3. The only inputs I really use are my laptop through USB and bluetooth, I connent my laptop to the tv through HDMI though but its just a very basic 1080p LCD

Now that we’ve covered all that, back to the main topic.
Since this is such a budget set up, I dont want to spend more than $100 on a receiver ideally.
Thats why im looking for something used, everything that seems decent enough new, tends to be around the $300 mark (although if there is anything that will meet my requirements for under $100 brand new, please share!)
The main issue im having is that I’m very new to HT setups and receivers specifically, most of the things im finding online in my budget, tend to be around 20 years old and I could sacrifice the bluetooth functionality if it meets every other requirements for the right price, but I just dont have a clue how any of these receivers match up to todays standards, or just my MX3 particularly, the last thing I wanna do is sacrifice sound quality.

Is there any particular models I should look out for?
or maybe certain brands after certain years that might fit the bill?
Im just at a loss here and I have no way of directly comparing the MX3’s sound quality to any of these old receivers im finding because there generally isnt much review about them online

Look for a yamaha RX-685-683 save up another $150 if you have too.