If you pay cash, then you are not covered by the Ebay Money Back Guarantee.
If you pay through Ebay, then get the item home and realise it is not what you expected, you can make a claim against the seller.
It is better for the seller if you pay cash, but not for you.
If you pay through Ebay, make sure you don't give the collection code to the seller until you actually pick the item up. If for some reason they don't make contact after you have paid, you can still open an 'item not received' case and get your money back.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)