$1000 to spend

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.

Spend it on your own time to bone up on PR and marketing tactics. There have been many posts on HN about this before so I won't repeat their advice, but there are probably popular blogs (and other sites) in your niche who could drive serious buyers to you if you're on top of your PR game.

Spend it on tickets and travel to the 2-3 biggest trade conferences in your industry. Make sure to set up meetings with target users/buyers of your product beforehand. This works a lot better in certain industries than others.

way more information needed to make constructive observations