I feel you!!
I just got a new bird and just yesterday saw another one for sale, a female, and a rare mutation yellowcheek pearl cockatiel. I almost pulled the trigger on her but stopped myself since I just got my new one. The voice of reason in my head tells me to wait, bond with my bird I have, and get a female next year. It is SO hard to make the right decision. My heart/emotions says YES, but my head/logic/reason is saying NO.
My advice... Remember your priorities. Another bird means twice the cost of food, another cage and split time between your two bids if they don't get along. Or if you were to suddenly get let go from this job, then you have no way to pay for their food and stuff.
My suggestion is to keep saving. Don't let the extra money fool you into thinking you can afford more than you can earn. Keep doing the full-time thing, get Lincoln's new cage and save -- I can't remember if you live on your own or at your parent's house still, going to college?
Remember that when you live on your own (which everyone does eventually) , you will have to keep that full-time job and pay for rent, utilities, phone bill, car insurance, internet, etc -- that doesn't even include bird stuff. What I'm saying is, just because you can afford another bird now, doesn't mean that when you move out in a year you will. you don't want to bite off more than you can chew now because your situation is ideal now, but will be changing in say, two years.
All those expenses will take up most of your paycheck, so be diligent on what you spend your money on now, you'll have to provide for your birds for 40+ years!