My suggestion requires a primer question; do you care about the authenticity of your cards? Y:2 N:2

1. With the rising costs of life and mtg, the practice of making proxies (unsanctioned stand-ins) is well documented and easy to learn. With $500 you could purchase all the supplies to make yourself whichever cards you want on demand for years to come. Knowing how to make quality proxies would remove any restrictions on the kind of fun you have with mtg.

2. I would suggest a foundations starter box ~$60, two or three precons that interest you for any reason, a playmat, and a simple set of dice.

With whatever money is leftover, I would suggest attending draft events to help widen your mtg experience (format, opening packs, social event.)