Have a search of this forum for others who haved asked "which box to buy" as you will find loads of posts with different info on boxes and different advice. Also look at the forum to see which boxes are popular and have recent/active support for them on here, no point buying a box no-one has or can help you with.
NEVER buy a gift from eBay, waste of money, get your line from this forum in the request thread at the top of this section. Members do share their supplier info with others, helps the suppliers earn money so they can keep the service running.
As per others comments, get the best box you can afford within your buget but do make sure you include every thing you need. homeplugs if your wireless is poor and your box is not close to your router, cost of a external HDD if the box you buy doesn't come with one or cost of a larger internal hard drive if the box you decide only has a small HDD in it and you record lots so need a larger HDD. ANy ethernet cables you need etc. All these things add up and need to be included in your budget.