If your budget is limited, I would do what others are suggesting - limit your target audience by location, scheduling, demographics and others. Also, if your budget is really limited, start with exact match for all keywords. Try making your ad group very small and targeted (max 15 keywords per ad group). That way, it's easier to bring the CPC down by increasing quality score. For super star keywords, I'd even consider having one ad group or one campaign for each keyword.
Take a look at Google Analytics (if you implemented one) and see what is the best converting time/day and where your customers are located for organic traffic. Use the data to adjust bids for audience to start with until you gather enough data for your paid campaigns.
You could also try RLSA and increase bids for those who match certain criteria. For example, you can use Google Analytics data to create audience who spent more than X minutes on your website. Then target the audience from your Adwords.
Happy marketing! Good luck.