While that is absolutely a function of marketing, another major task of marketing that often goes neglected is growing revenue from our existing customer base (a third is activation of lasped customers, but we'll save that for another time).
And there, my friend, you can find a bunch of cheap marketing tactics that will work well to grow your business.
Let's take a classic loyalty program tactic - the bounceback program.
These can take a many forms - I'll focus on a couple that don't require special technology or equipment and can be done for very little cost.
THE PUNCH CARD
This is old-school, and cheap. Make up business-card sized punch cards - have your customer get a punch every purchase (or after spending (x) number of dollars). After so many purchases, they get a reward.
Pros: easy to execute and promote, inexpensive, low-technology
Cons: people forget they have them, almost impossible to track results
Variant: What if you did this as a referral program? Existing customer gets so many punches for referrals, getting a really good reward after the card is filled?
BOUNCEBACK COUPONS
These kinds of coupons are usually given after a purchase is concluded, in order to incite a return visit (a "bounceback"). Make sure your coupon has a relatively short redemption window - first, because you want them to return quickly, and second, because they will forget they have the coupon after too long a period.
Pros: easy to execute, inexpensive, low-technology, easy to track results if coded properly
Cons: people forget they have them, doesn't work well for businesses that have a long repurchase window
Variant: If you have a long repurchase window, make this coupon a "refer a friend" coupon. When the friend's coupon is redeemed, the person who gave out the coupon gets a reward
Do you have any favorite cheap ways to "bounceback" a customer? Let me know in the comments!