Absolutely. There are so many shades of grey. Far more than 40 in fact.
On the one hand, if you are in business, it would be insanity not to take advantage of major price rises. On the other you don't want to alienate your customers through transparently obvious sharp practice. So it's a matter of flexibility. Recognising market movements, but also not unreasonably inflating your prices to rip off levels. Not deliberately trying to take advantage of newbie collectors and so forth. Not lying about a variety or exaggerating a grade.
If it was me, I might be open to offers, free with technical advice or pointing in the right direction if I didn't know, and maybe throw in the odd freebie extra now and again, especially for long standing customers.
Like you, I'd want my customers to see me as a friend, as much as a trading contact.
At the end of the day though, honesty and integrity aces all.