Hi Bigeye,
You must do your own homework before bidding on Ebay, i.e. finding out what an item costs. I am a Sea Angler and time and time again I have seen people pay well over the top for items that can be purchased cheaper from a conventional outlet. You must also remember that the cost of postage must be taken into consideration.
I have had my Mountfield 18" petrol mower for over 25 years now, and it has never let me down. It is cleaned every time I use it and I change the oil every year. No doubt other people will give you advice on what to buy, in the long run it is entirely up to you.
regards
Drew