Actually I see some draw backs, for future sales you may consider another option.
Ebay FROWNS on "sellers" that Charge these LARGE ship/seller fees as it is usually a seller looking to keep his list price low and then "make up for it" in the shipping, which is not permitted AND dishonest in my opinion. Seller gets charged lower fee by ebay for the "low" listing and MANY do this to make extra off the public. So, thats how YOU'D look (wrongly of course)
By saying that you "charged extra" COULD be later used by that buyer to say they were hit with UNKNOWN fees but did not agree to it (like they never got the extra's you actually sold them.) Especially if a charge card was used, the charge companies return the money faster than you can blink and you'd be out of luck or atleast having to go thru the hassle of trying to explain what REALLY happened.
Or if there is a problem with the transaction, item does not show up, or they claim it showed up damaged, what is the REAL value, just so many issues can pop up.
It was kind of you to agree to the price, WHO KNOWS, some people ESPECIALLY if they want something pay crazy prices, so you could have also cut yourself out of some "extra" money.
You could have offered to set it up as a BUY NOW if they were interested they'd just buy and pay it and you could have Combined Ship if you were so inclined. Or you could have let them know that another listing would be up (whatever time frame and likely they'd come right back).
Unfortunately I have found (over 300+ auctions) that MANY more people than I ever anticipated were really NOT very honest, and thats sad for everyone on ebay. Ebay can be a fun profitable place, but you really need to be on top of everything too.
Good Luck, hope this helped! (personally I use Craigslist way more now)