What should I buy with a $500 espresso budget?
Reserve about $60 to $80 for a scale, a precision basket and a WDT tool, then split the rest with at least half going to the grinder. That usually means a capable entry grinder plus a used or entry PID single boiler.
At $500 all-in you are buying a real setup with real compromises, and the way to avoid disappointment is to decide which compromise you are making deliberately. The three candidate shapes are: a new entry machine plus an entry grinder, a used machine plus a better grinder, or a manual lever plus a good hand grinder. All three make genuinely good espresso. They fail in different places.
The used route is the highest quality per dollar and the highest risk. A well-cared-for older single boiler with a commercial 58 mm group can be had for a fraction of new, which frees real money for the grinder. The risk is scale, tired gaskets and a seller who does not know what they have. Ask for descaling history, ask to see it pull a shot, and budget for a gasket and shower screen the week you get it.
The lever route is the highest ceiling and the lowest convenience. A manual lever plus a good hand grinder fits this budget comfortably and pulls shots that embarrass much more expensive pump setups. The honest trade: steaming milk is limited or absent depending on the model, and every shot is a small ritual. If you drink straight espresso and like process, this is arguably the best coffee available at $500.
If milk drinks are the point, the picture changes and gets harder. Steam capability is the expensive part of a cheap machine, and $500 buys a machine that steams adequately rather than well, which means a slower, wetter stretch and less forgiving latte art. That is survivable. What is not survivable is pairing it with a grinder that cannot hold a fine setting, so still protect the grinder half of the budget.
Whatever shape you choose, do not skip the small items. A 0.1 g scale that fits under the group, a precision basket and a WDT tool together cost less than a tenth of this budget and improve more shots than the difference between two machines in the same price band. This is the least exciting spending on the list and the most reliably rewarding.