To be honest if you are running motors and an attachment such as a laser or engraver motor you want to be looking at around 10 amps for long term reliability.
My most reliable rig has a 20 volt 12 amp and a 12 volt 10 amp supply and has never glitched since I put those in.
Yes its a little more expensive but worth it in the long term.
My other rig has a 12 volt 8 amp supply with NEMA 14 (x3) motors, Crossflow fans (2x60mm) and a 2.5w Blue laser, but struggles a little with everything running so I have just ordered new supplies for that too.
Account for future plans if you can such as crossflow fans for laser work in push pull configuration.
Or a 4th axis for special work. If you are using EBay then 25-35 US should put you in the right prices bracket for a decent supply but its always worth the extra 5-10 US to go from 10-15 amp to something like a 20-30 amp.
Glad to have assisted.