Referrals, and networking. I get the challenge of niche positions with limited budget. Use Linked in to reach out to your network, people you know personally or connections that may be able to refer someone. If you have folks in your company who do similar positions it's good to connect with them as well... we value referrals over agencies any day. 

I agree with Jillian, referrals and Linked In are great resources.  I would also look at local user groups.  Most communities have an active IT group made up of people of various skill sets who meet regularly.  Find a group that forms around the skills you need, or something very similar.  Plugging in with these folks may lead you down the right path.  Also make sure you have a compelling job description written up that talks about your company and what makes it great, why people love working there and what they get to accomplish everyday.  Most job descriptions are boring and are overlooked.  

We try on our own for about 90 days but if that doesn't get us some great candidates we use Joe Leister at Blueprint. He always seems to come up with a winner when we can't get there ourselves!

Our IT Director had me post to Dice.com , you could look into that ...but we are still struggling to get candidates. I think it is just difficult right now.