University of ghana forms can be bought at any bank that the university approves of. Currently Ecobank, Ghana Commercial Bank, Standard Chatered Bank are known to be the banks of choice for purchasing legon forms.
First you have to buy an e-voucher at the bank. The e-voucher will contain an id number and pin which you would be required before you can login to fill your forms online at legon's website http://ug.edu.gh.
The e-voucher will cost you around 100 - 120 cedis and that is the price for the application form.