Danielle, that's sweet of you to want to help this guy.
Since you mention there are other cats in the area, and since it seems like you do want to help, if you have the time, you may want to put a little bit of work into seeing if there are any rescue groups or individuals in the area that can help.
I don't know where you're located, but here are a few ideas for finding something other than the SPCA and the other shelter you're familiar with.How Can the Best Friends Network Help Me?
The Best Friends No More Homeless Pets Campaign is a growing network of people around the country - you can sign on in order to find help for cats in your community.
You can call around to local area vets (anonymously if you wish) to see if they're aware of any groups or individuals that work to help stray and homeless cats OTHER than by picking them up and taking them to the SPCA or working with animal control (both options usually end up in the cats' death).
Contact Alley Cat Allies (www.alleycat.org
) to see if they have anyone volunteering in your area.
Perform an online search for no-kill rescue organizations or feral support groups. Click on the Rescue Resources link in my signature line, and it'll take you to a number of links where you can search for such groups. Even if they're not immediately located in your area but are within a few hundred miles, it's worth giving them a buzz to see if they don't have anyone in the area who can help if they know of anyone who can.
This way you may be able to find some help for the other kitties as well as this young stray that has taken a shine to you.
And kudos to you for "knowing your limit." That's one of the first most important things anyone involved in rescue has to contend with.
Good luck! Please let us know if you find anyone who can help.