Ever wondered why so many heavy metal guitarists in the 1980s had long hair? By growing your hair long (and thereby saving the cost of haircuts), you can save enough money to finance your next guitar.
If the average price of a haircut is around £10 ($20) and you have a monthly haircut , by letting your hair grow in 3 years you could raise £360 ($720). Enough to get a new guitar!
As a bonus, when your hair gets really long you can cut it off and sell it to a wig shop, raising even more cash.
Disclaimers: This will not work if you are bald or cut your own hair. Shampoo usage may increase, cancelling out any cost savings. Always remember to tie long hair back when operating machinery.