How long has it been since you've had surgery (assuming that you HAVE had surgery)?
Pellicle has good information and recommendations for managing your INR. Warfarin is very slow acting - results from a dose today may not show much (or any) effects until the third day. You have to modify your dosage in small steps in order to bring and maintain it in range. Large changes every few days will make it unmanageable.
As far as diet is concerned, just try to be consistent with your diet -- this will make it easier to find the dose that's right for you.
As far as machines for testing are concerned, you should be able to occasionally find a meter on eBay that is priced affordably. I've seen some Coag-Sense (sometimes called CoaguSense) meters on eBay that are priced pretty low. For me, this is my meter of choice, so you shouldn't be afraid of buying one (as long as it comes with a DOA or other warranty and the seller has a good feedback score). I've seen test strips selling for a few dollars each. (In fact, I've got an extra meter that I may be interested in selling).
You can occasionally get a good price on a CoaguChek XS. DO NOT buy a CoaguChek S, or an InRatio meter -- these have been discontinued and you won't be able to get any test strips. Either the people who try to sell these are unaware that they're worthless, or they're just crooks trying to separate customers from their money.
Also, if you buy strips, check the expiration dates. Figure that you'll probably be testing weekly once you get your INR under control and don't buy strips that will expire before you can finish using the batch. If you're buying CoaguChek XS strips, make sure that you get the code chip for the strips that you buy.
You don't have to be rich to afford self-testing and self-management. (Take it from me - I know these things).