Isopropyl Alcohol (IPA), or rubbing alcohol as it's called in the USA, is most commonly used for this purpose in audio servicing workshops. The tape type of cleaners collect the crud but it's gets progressively more difficult to remove from the tape over time.
Buy 100ml of IPA off ebay:
http://www.ebay.co.uk...at=See-All-Categories
100ml of IPA is really cheap and should last you for years. Just be sure to apply it with a lint-free type of cloth rather than a cotton bud and keep it away from children and heat sources.