Consider sponsorship. I don’t mean the high profile TV ad type of sponsorship (unless of course you have the budget and it works for you), I mean sponsor an event that they are likely to attend where your brand can be put in front of them and raise awareness in an uncluttered environment.
For example if you are targeting law firms, what about speaking to the regional branch of the Law Society nearby to you and offering to sponsor their next event. Usually you will pay for food and drinks but will be given an opportunity to display your exhibition banners, give out marketing material and even say a few words as the sponsor about your business.
There are numerous ways to use sponsorship effectively and without spending a small fortune, you just need to get your thinking cap on and be creative.