i have 2 biorbs a 30L and a 60L, i paid £50 for the 30l including all the equipment,(used) and £129 for the 60L inclucinding all equipment and a led light (brand new)
i could have easily got a 4 ft or larger for the prices on ebay.but i just didnt have the room for them, i love my biorbs, they are both in my bedroom at either side of the bed, the 30L house a male betta,and the 60L has some neons and is planted, they do distort the shape/size of the fish and the fish can actually go out of veiw, but this isnt all the time, and i wouldnt part with mine for all the money in the world,as long as they are sensibly stocked, there should be no problems,and for a betta on his own i recomend them, mine is very happy, i have never had an issue with the tank or the fish since the day i put him in there, but the filters are not that good ( so others say)and there isnt much surface area, so fish have to be well reaserched before adding them to ensure they are suited. no bottom dwellers ie,cories.loaches. but yes i would say go ahead and grab one, they are often on ebay in your area, i know, as i get dissapointed as i cant get to them over there
you could try the adverts that come up on the bottom of the pages on ebay,as i have ofteb searched these and come up with some bargains, and most of them offer free next day delivery, but if you go to pets at home or acorn or such like, get an idea of the price they sell for then you will know what NOT to pay,i garantee you will get one much cheaper thjan they sell them for, or even if you have a spare heater at home( you will need a heater stand£2) ( 50W) you could go for the coldwater biorb which can be a bit cheaper again, but i would defo make sure you get one that has a light with it,as these work out to be very expensive (20-halogen,45-led) if you decide to add them later.
good luck whatever you decide to do
shelagh xxxx