Used tanks often come with a stand, top, filter, light (all quite possibly old) & a questionable heater. We here in the US often see good deals but also not great 1s too. Some sellers think because they paid $200+ for brand new 20- 55g stuff, it should be worth almost that much used. No! That's wrong. In large markets (like yours & mine) you can expect to pay $1/gal for tank & maybe some iffy stuff or $2/gal for better. Their neon gravel, tacky decorations & ancient food & meds are worth nothing! But high end rimless low iron tanks, LED lights, (or Kessils!), CO2 set up etc. cost a lot more, even used. But a "deal" only if you'll use them & they still work or you can get replacement parts ( easily & affordably).
Research a lot! I give bare tanks, plants, fish etc. away to club members, but hoard things like filters & even rocks & substrate I like, lol. Somebody's salt water set up CAN be used for fresh but will come with expensive things you won't use & the tank maybe etched. It's very not often worth it.
Resealing tanks is not very hard but is a bit intimidating, if I can do it (& I have many times) you can too! Be careful of "junk" particle board stands.
Plan to bleach everything! There's a good reason they're opting out of the hobby, likely a "plague" of some sort that killed all their fish.
Educate yourself before going into more tanks. Even "new" may not come with the good equipment you will want or need to replace in a year or 2.
Don't be in a hurry, we know you're excited with cory eggs & all!
Spring is often a good time for deals, be prepared when they come.