Thanks for your reply fuster
Based on what you said there absolutely should be deals because I think it can both pull in more donations and donations of a larger size.
I think one possible good idea would be holiday "sales". There is always an influx of new players around holidays as people have more free time, e.g. at christmas, easter and summer. I think maybe, half price on all admin costs for example during limited periods in the holidays may attract more people to JAG. This primarily would be a way of bringing in new players and donators.
On the other hand deals such as buy-one-get-one-free will increase the size of donations and can be implemented all year round. This will play more prominance when JAG is at full capacity and has a range of servers fully operational. Examples I can immediately think of might be, buy one server get another half price. Or buy two, get a third free. Maybe have a monthly promotional deal such as: this month get the bundle of jail mingame and deathrun for half price for example.
These are all very basic ideas and of course have to be discussed fully with exact details to be decided, but just a few possible things to consider