Sadly, on a budget of 500 (though he doesn't say 500 what - if it's Lira then he's really had it

) the likes of Wendt, SQN and the other better quality ENG/shoulder hanging mixers are out of the question. Even an Audient ASP-008 is over-budget and doesn't get one any closer to mixing signals.
Quite a lot of classical location recording outfits/engineers use Mackie VLZ/VLZ-Pro mixers. The preamps are pretty good - clean, neutral and quiet. There are many better preamps - especially if you get into stand alone stuff - but for the cost per channel they're quite hard to beat. (And that's coming from someone who really dislikes Mackie mixers!

) If you go the Mackie route, avoid using the EQ - it's horrible (just a personal opinion of course

) - and the mix buss is nothing to write home about either but, with a little care they're capable of very respectable results.
When I need to go really portable (and/or run off batteries) I have a small Sound Devices ENG mixer (a 442) and a Sonosax SX-PR, either of which would be a good choice but they're a fair bit more than 500 anything and only accommodate 4 (or 6) mic inputs. My own preference for a cheap, small(ish) location mixer in this price range, would be a used DDA (or Dynacord) Interface. An 8:4:2 is easily movable by one person and is available as either a table top (with plastic trims) or rack mount (in squared off metal case with built in rack ears). They go for about £250-500 depending upon age/condition/specific channel setup (they're modular on a per channel basis and there's several different channel options) and case version. The EQ is ok (if you want to use EQ) and the mix buss is clean, fairly transparent and has decent headroom. The master section is rather basic (only one 2Trk return and one Monitor (speaker) output) but it does at least have an oscillator! There are a few simple mods which can raise the sound quality a little and there's enough room in the case to add a few extras like cue light switching/extra talkback to reduce the box count on location sessions. The separate (2U) PSU is a bit of a bind as it's fairly heavy - as is the mixer, for it's size - but the sound is imo preferable to any Mackie and the build is much stroger and more reliable. I know that Tony Faulkner uses a 16:4 Interface on some of his work. He seems happy enough with it and the results are up to his usual high standards.
I use an Interface sometimes (I have a 16:2 (8 mono mic/line + 8 stereo mic/line) rackmount, and a few others of different sizes which occasionally are used for classical recording/broadcast work and which are hired out when I'm not using them) and I have few complaints about them. They're reliable, easy to use, physically fairly compact, and the prefader direct out with it's own level control (only on the mono channels) can be very handy, especially on larger jobs where a multitrack backup is wanted.
Other consoles I have include, amongst others, a Calrec, other DDAs, Neves, Studers and Summit Audio - no Mackies though

All of which get regular use on classical (and other) recordings/broadcasts but most are out of the price range in this case - though some, if bought used, not really any more so than an SQN.
I recently worked on a live orchestral recording for webcast with a very well known classical engineer who surprised me by using a a Soundcraft FX/SX (I can't remember the number but it was about 12-16 channels and physically small/light). It sounded fine. He has many other, more esoteric, mixers but the "control room" was the size of a broom cupboard and up several flights of stairs. His comment was that as long as it was clean and quiet enough to mix whilst staying sonically out of the way, the mixer was all but irrelevant on this job. Far more important is the choice of mics and positioning, and the A-D converters - and the ability to pick up the mixer in one hand, easily carry it up stairs and balance it on top of the recorders as there was no other space available. A choice dictated by pragmatism rather than preciousness over tiny sonic details that most people would miss and which would in any case be lost on the webcast. The Soundcraft sounded surprisingly (to me anyway) good and it's size and convenience would put it on my list to check out at this price point.