money...but the radio is essential
my former department serves a very small town of about 600. Currently two radios are assigned to each apparatus. The engine can seat three, but two are already available for the truck and the same goes for the squad. Additional radios are in a radio bank by the door as you enter the station, so you grab one as you head for your gear. This is SOP for all personnel to have a radio when operating on a scene. This has helped during PAR's and even when members have had to use the little "orange" button.
However, this has not come without a financial burden to the department. Several used radios were purchased to get the number of radios available for each apparatus AND with re-banding the department is now applying for grants in order to communicate with not only our dispatch center, but also all FD's in the area. Money has been an issue, but the expense is well worth it and I am hear today because of the rule every member caries a radio.