You can always make your own terms, However those terms cannot be against ebay rules
for example you cannot say, I only accept cash (ebay rules only allow paypal for shipped items)
And you cannot say JEWS ONLY, discrimnation is against ebay rules and the dispute resolution , eBay is very specific about dispute resolutions, you have to accept their eBay resolution service.
BenBagBag,
Do you actually sell on ebay, or are you just saying what you think the law is. ive been on ebay for some time , ive sold Millions of dollars on ebay. I know the rules, you have to know them otherwise they will kick you off