New job prospects

I sent my resume to another company the other day and I was called back for an interview. I know someone who works for the company. He's actually the one who called me about the job. I wasn't really looking for a new job, but he thought that this particular opening would be perfect for me and the department has a reputation for paying well. So, he gave me a call and asked me to send him my resume. I did and got the call. He said that they're excited to meet me because of my unusual skill set which happens to be exactly what they're looking for. I've worked two parts of a particular job that most people don't do.
This is a good chance to seriously bump up my income level. I'm talking about a 12k bump if not better. I'm pretty nervous about it because I really want that bump. If I don't get the job or if the offer isn't as good as I'd like it to be, it's not that big of a deal since I have a good job. Like I said, I wasn't really looking for a job. I'm happy where I'm at, but the money could be better. I feel like I was slighted at raise time this last year. I especially feel slighted after find out what a couple of other people in my same or similar positions got. Bonus time is in February and I was going to wait and see what bonus time brought for me. If I got a good bonus then all would be forgiven, but if my bonus matched my raise...which was disapointing, then I was going to look for a new job. Of course, if this works out for me, then I won't have to worry about that.