Sarb, there is always a small cost associated with receiving a payment online. I run an online retail shop that uses both PayPal and a Merchant Account. Here is the scoop...
Paypal would be very good for what you want to do. All you have to have is a bank account they can transfer your collected funds to. You will pay a small fee for their service - figure about 2% of each donation that people make. People can easily pay with their credit or debit cards. It is very safe and simple.
A full Merchant Account allows you to take credit card payments directly, but it is much more complicated. The per transaction fee is less than PayPal (maybe 1.5%) but all the other fees the processing companies add on really add up. This type of account is only good for those who do enough transactions that the % savings are greater than all the other fees you have to pay.
For what you described, Paypal would be best.