The asking price is too high, IMO. I sold a wonderful 16.1h 6 year old with no stop, no spook, no buck, wonderful manners for $7,500 (of course then 3 months later the buyer tried to resell him for $15k), gorgeous dapple gray.
If you love the horse, make an offer. I used to love the tricky ones :-) And the definition of tricky seems to be narrowing. In my world, what you described would be just an ordinary horse :-)
I think for $7500 i expect the horse to have a decent lead change. Especially, since he is not registered, and you really don't know what he is, or likely where he came from. I'm currently selling a really gorgeous 7 y/o TB for $7500, and he has a ton of (mostly local, some rated) show experience, solid lead changes, and is super honest. I still consider him priced a little high for what he is, but I am in no hurry to see him go, either. I say why bother with a horse who may or may not be a stopper and who may or may not ever have a decent change, when there are so many out there who already have these skills? If you really love him, offer $3500, and see where it goes.
Interesting insights into reasons for buying a horse - or not. I think that buying one's first horse is always a risk. A plus about this one is that she knows its faults already and presumably isn't doped up before she gets to ride it.
At 23, the OP has plenty of time to learn about selecting a horse, and if she bought this one, and it didn't measure up to her highest ambitions, would it REALLY matter? She is young, and we all know that it takes a lifetime to learn all about horses - don't we?
What she will know is how to judge a horse, what she wants in the next one, and how much to pay for it. Her horsemanship will improve too - she will learn how to ride a 'rude' horse for a start (and maybe correct the attitude, lol), and if she can demonstrate that he can go round then there will be a buyer for him in a couple of years or 3.
I'd offer 4k, if the 'melanoma' passes inspection, the horse is sound, and negotiate up some. And get him measured.
Seems overpriced to me too. But the biggest red flag is the melanoma. These are benign tumours in horses (unlike people), BUT when you have one starting at the age of 6, there will likely be a lot of growth over the years. They CAN be debilitating even when benign, as they often eventually impinge on important structures. I have seen an older TB that could not canter anymore because the melanoma on his neck affected his breathing quite a lot. Another older grey that had to have rectal surgery because the tumour was blocking that area.
I would want an experienced vet to give an opinion on this, and I would also do extensive research on the internet as well. Melanomas in greys are typically slow growing and benign, but when they start in a 6 year old, it does have the potential to become problematic in addition to becoming increasingly unsightly.