10 $100 lunches with people who can connect you with people who will buy your product, or lunches with your engineers about who would buy the product and how to pitch it to them.

Give away a copy or two or a few months service for customers that recommend another customer. Can do the same with employees that refer a company to you.

Old fashioned letters. ($1000 will go a long way in stamps).

An advertisement in a trade magazine. Or, conversely, quite a few subscriptions to trade magazines where you find out the names of companies who are looking for what you sell.