in order to get a good IR results you should go into older nikon models. Newer one have a little more resistance to IR waves thus take longet time to produce image. From personal experience D700 take 6-8 seconds longer to take a photo then D70
My recommendation is to get D70 or D70s for very little used and start there. You could also look into D200 which does great job as well.
What I would also recommend is to try IR first and then plunge into converting body. My suggestion get yourself Hoya R72 filter and see if you like it first - if you do go ahead and get separate body for it. If you dont .... sell it for little loss and be done with it. Personally I have R72 77mm filter all the time with me that I love to use for very strong black and white images.
