"Paypal" is a verb, now, is it. 🙂 If you had bought the tickes, 'Zeus', the seller would have your email anyway, so it's not really a big deal. But as you have merely expressed an interest by offering, you seller wishes to send you an invoice for the tickets and avoid paying ebay fees. Very naughty. Certainly not 'ok', at least not by ebay policy.
You have a very low feedback and consequently some sellers will endeavour to take advantage of you. So in a sense, you could use that newness to your own purpose by kindly explaining to the seller that you wish to go through ebay for the transaction because you need to build up feedback. You don't even have a 'star' yet.
If the seller has tickets for sale with a "make an offer" option, the proper procedure is for you to enter your offer, and he either accepts, ignores, declines, or makes a counter offer. If he accepts, it is in your Purchase History and you pay. If he declines, you can make up to 2 more offers. If he counters, then you can choose to accept, ignore, decline, or make a further counter offer. But an off-ebay sale done on the sly from one paypal account to another is a no-no. If you want to see ebay's official position on this, here is a link to tell you more:
http://pages.ebay.ca/help/policies/rfe-spam-non-ebay-sale.html
