$500 total to get into vinyl, what would you buy?

If you need to buy a phono section in addition to the analog rig, you'll need to consider at least $100 for that.
I think a Planar 2 with a lower cost Goldring cartridge and a Parasound or Sumiko phono stage, could be gotten for under $500 for all of it.

This would just barely be getting you into a decent quality rig, and would not really be representative of what vinyl can be, but would be a good start. The tonearm would be the best part of the rig, and could be modded to take you quite a ways up the scale, moved on to a higher table. Everything else could be considered expendable when you upgrade.

About 8 months ago purchased a used MMF-5 TT in pristine condition and am very very pleased with it. I like the fact it comes a very good cartridge standard and offers very good platter isolation.(Something to consider if you have kids or if people's footsteps around your rig are an issue.) My TT does have one design feature with the cueing mechanism which you have to be careful about. Namely, if you bring the tonearm too far to the right(away from the platter) the cueing arm/level in the "up position" will not prevent the arm/cartridge from hitting the base. Perhaps newer models are different? Just have to exercise a little extra care. Overall, a great TT and a wonderful way to re-discover/discover vinyl.

Hi Socrates, once in a great while I have seen the Well Tempered TT with the W.T. tone arm for $500. An excellent TT even if you may have to spend an extra $100 or two. Keep an eye out. Not one of the best looking TT but will compete or better many high priced CDP. Like Kotta said "A wonderful way way to re-discover vinyl". IMO, a true classic. Good hunting.

I'm listing my Sota Comet, LMT III arm and practically new Grado Gold Cartridge for $500. Like you, I bought this rig to dip my toe back into analog. I was so impressed I'm upgrading to a Nottingham Spacedeck, arm and Grado Sonata cartridge. The Sota is dead quiet and has never mistracked even under heavy footfalls. Highly recommended.

Mark

I bought an MMF-5 and a Monolithic Sound PS-1 to transfer some of my old records to CD here at my studio; and the combination is really quite good. In fact, I've now got several people bugging me to transfer old vinyl for them too.
The MMF-5 is quite easy to set up; and has pretty decent isolation as well. If you have a preamp with a phono section you will be all set to go. If not, you may want to look into some of the lower cost phono sections, such as Creek. The Monolithic is quite a bit more expensive - about $400.00 - but does seem to match quite well with the MMF-5.
One last item - the MMF-5 that I purchased was a demo unit and I got if for way below the list price. You might find one here on Audiogon if you look hard - or maybe at one of your local dealers. It is a popular item - so I suspect locating a decent lightly-used unit should not be too difficult. Happy listening.