Someone paying 10 for a wrap of speed is spending 50 pence on speed and 9.50 on everything else that's in it. Amphetamines increase metabolic rate, and will use up stores of nutrients in the body. Someone using speed will recover more quickly afterwards if they replace essential nutrients like Vitamin C and Calcium, and rest properly. Using speed causes an increase in heart rate, blood pressure and body temperature. At high doses it is possible for your heart to go into arrythmia - it starts jumping about all over the place.
Body temperature can soar, causing overheating.
Taking speed with other stimulants like E increases these risks. Amphetamine use can affect sexual behaviour. Male orgasm and ejaculation are inhibited. Sex can last for a long time. Make sure that you have plenty of condoms, just in case.