Cheap but good exercise bike?

Looking for an exercise bike, under 50 pounds. Already checked the obvious ones- tesco, argos, asda, ebay etc........and ideas would be much appreicated!

http://www.amazon.co.uk/Ultrafit-331100000022-F-Bike/dp/B003FSTA0U/ref=sr_1_3?s=sports&ie=UTF8&qid=1316622602&sr=1-3 http://www.amazon.co.uk/V-Fit-Folding-Frame-Magnetic-Cycle/dp/B002Y5XHVS/ref=sr_1_9?s=sports&ie=UTF8&qid=1316622...

http://www.amazon.co.uk/Starshaper-KC143-Exercise-Bike/dp/B00322OZD6/ref=sr_1_4?ie=UTF8&qid=1316587445&sr=8-4 is this exercise bike good, will it increase my stamina and will it make me run faster. i am trying to run really fast for a very long...

http://www.argos.co.uk/static/Product/partNumber/9237386/c_1/1%7Ccategory_root%7CSports+and+leisure%7C14419152/Trail/searchtext%3EEXERCISE+BIKE.htm what are the benefits of this exercise bike and what can it do to help me. and is this exercise bike good...

I plan on buying a bike tomorrow and aiming to ride up to 10 kms every day. I am obese and have much weight to lose and on a healthy eating plan. I aim to boost it by riding my bike each day. Is this good exercise? I am even going to the shops on my...

Is 40 mins a night good on a exercise bike? Im trying to get fit and burn fat. I stick to a 1500 calories a day diet, drink plenty of water and green tea. Eat fresh fruit and veg. I also play football one night a week for a hour. Every night i go on...

I was planning on getting an exercise bike to get back in shape little by little. I figured that this would be a good way to get back in shape because when I was little I used to love to ride my bike. Also, is an exercise bike the best way to get back...

I have a standard exercise bike, and I'm just wondering what a good distance in terms on kms would be? I've been doing 20kms and it takes me about 30 minutes.. is this good? Which burns about 500 calories or more. I just don't know whether this is good...

I was thinking of hitting the gym since i want to loose weight this year, however i dont want to have to pay since im on a budget. but im thinking of investing my money on a bmx bike. I havent had a chance to ride a bike for years so i think it will...