In terms of “adoption fees”, the money really is not a fee but rather reimbursement of the basic medical expenses that we incurred, and that varies from cat to cat. Note that this does not include cost of flea meds, ear mite meds, antibiotics, food, litter, urinalyses, blood work, surgeries on sick animals, most dental work, grooming, food, litter, supplies,… Any of those interventions we usually don’t recover and have to pay from personal savings (which, if you figure in how MANY cats need those interventions, runs into double digits of thousands of dollars per year, sadly enough). While the reimbursement varies from cat to cat, I can give you the general pattern for “fees”:

• To get them vaccinated (usually the “starter set” of two feline distemper vaccines, plus a rabies vaccine which must be given by a vet thus requires a medical exam and an exam fee) and tested for FIV and FeLV -- all of which is standard procedure -- I pay $150, which I would like to recover in full. This amount constitutes a discount rate, as we get “mass discounts” due to the number of animals we take to the vet, and due to the vet wishing to support our rescue efforts.
• All cats get an ID microchip so that, should they ever accidentally get out, you can be identified as owner and reunited with your kitty; since I get rescue discounts for both the chip and the registration, I get this done for a one-time fee of $25. The chip stays active during the cat's entire life, and contact info can be updated and changed as necessary. (Usually, at a vet clinic, one pays between $55 and $95 for the chip plus registration...but knowing that adoption also has a price tag attached, we work horribly hard to do most of the work while the cat is in the rescue thus gets rescue discounts, and to ask for reimbursement of those low costs from the adopter).
• If a cat needs to be spayed (female), then that adds $50, while neutering a male costs $45. But older cats usually were previously spayed or neutered, which gives a financial advantage to balance the age disadvantage. We do not ever release cats unaltered, it's a matter of policy and our unwavering commitment to help with the cat overpopulation. It's either we spay/neuter prior to release, or people need to get a cat someplace else.
• If it helps in doing the math, please take into account that I am willing to accept two half-price checks to spread out the payments. Also, please consider that having a pet is and always will be expensive, no doubt about that.
• Please take a close look and truly compare “apples to apples”. When you adopt from a shelter for only $25 or so, then usually the cat has only its first distemper vaccine, if that. Which leaves you with another distemper vaccine, plus the rabies vaccine, plus a vet visit, plus the FIV and FeLV tests (because you really need to know what you are dealing with)... and you'll be above the $150 before you know it. Unfortunately, shelters don't say that outright, as to not scare away adopters... but it makes us rescuers look like vultures when, in fact, we offer a great deal in that all the vetting is already done, and done cheaply, and the animals are cleaned up and healthy (which is particularly of importance with longhairs that tend to be a mess when they get dumped, like the Persians and Himalayans). Also, remember that county shelters, as government-subsidized operations, get supported by your tax dollars and mine; out of the home rescues don’t get that privilege and have to manage on personal savings, thus are always much more threatened by bankruptcy than shelters. Yet, little rescues often do a fabulous job in physically and emotionally rehabilitating cats that, frankly, in shelters would simply get euthanized. So, when considering “fees”, please understand that your money helps us to keep going on with saving lives… these moneys are definitely not for personal use or fun or bureaucratic overhead, trust me.