If it's a startup, they probably don't want to pay you top dollar. The might just not have it. I wish startup management would be honest about the dollars in investment, And how much they themselves make. I also wish that everyone in a startup got a good size of the pie.
On the good side, if the company grows, you might be in the right spot. Options will likely open up. And, having a successful project on your resume usually helps for the next job.
100k/y. I think 80K/y is low, if your efficient and good, and are getting no other benefits actual, or otherwise. Consider health care, 401k plan, profit sharing, paid hols. What's your commute like. Do you work more then 60 hrs / week, or more like 30 hrs in the office, and another chunk at home. Lunch, gym, pool table, model plane runway? Do you enjoy work, have friends. Add it all up? $100k/year in a hell hole, might be worse that $80 where your at.
Also, is your company making money? Are you likely to be employed for years? In this economy you might be lucky to have a job. Startups can scary places.
On the good side, if the company grows, you might be in the right spot. Options will likely open up. And, having a successful project on your resume usually helps for the next job.