I was in Tesco the other night and noticed that their activequipement range of bike gear is back on the shelves (it had petered out previously, then come back rather expensive).
Anyway, some examples of the kit, which I've found to be pretty good quality overall.
bungee microLED lights, pair red/white - £3.61
single red or white bright LED light with velcro mounting: £3.61
Track Pump (up to 160 PSI - £14.98
Cycling Top: £12
Cycling shorts: £8.47
Saddle Bag, includes quick mount/release kit: £6 (I think)
Cycling computer (with cadence!): £14.68
More which I can't remember off hand, including very inexpensive inner-tubes.
Some are available online, some are not.