You sound like you are in the same boat I was in before I got mine. I thought I would save money and buy a used one. Bad mistake.
While it 'kinda-sorta' work, it would sound off if I held the cord wrong. Long story short, it needed repair, and, by the time I was done, I had less than 10$ shy of new price in it.
That was 2 years back, with no problems since. I understand the earlier ones had problems with the cord, and they have that corrected nowadays.
As far as it being worthwhile, YES!!!! You can get an accurate ID and depth on 90% of the coins you find. The best part is it will help you sort out the small bits of junk that read as a deep coin when you have the gain cranked up. If the probe will pick it up, you know it is not down 8".
Cash in some clad, bite the bullet and get a BRAND NEW one, and you won't look back with regret.