Stores in the D.C. area are reporting a rush of sales as buyers scurry to beat Saturday's deadline for electronic smoke detectors. The new D.C. law says that if you don't have a smoke detector in your home by then, you could be fined $300 and get 10 days in jail.

So you're a homeowner and do not have a smoke detector, what is your best buy? It may pay to shop around. Some consideration:

Basically, there are two types of detectors:

Ion-exchange detector. Senses combustion particles from flames. Particularly effective in quick-developing, flash fires. Least expensive, and most readily available.

Photo-electric detector. Uses a photoelectric cell to "see" smoke, usually costs a little more and is harder to find. More effective in slow-developing, heavy-smoke fires (the most common).

Both types of detectors will give you adequate warning for quick-flame or slow-smoke fires.

For pyro purists, there's a super detector that combines both ion-exchange and photoelectric cells. Sears had this type listed in its catalogue for $29.99.

Here's a quick price comparison on the simplest battery-operated, ion-exchange detector. (Watch sales for even cheaper prices.) Because similar-type detectors provide comparable protection, your choice may depend on which store is closest to your home:

Montgomery Ward, $9.88; Sears, $10.88; Dart Drug, $14.97; Hechinger's, $16.99. Other stores, especially the chains and hardware outlets, may also carry smoke detectors.

The Sears catalogue also has a battery-operated, photoelectric detector ($16.99). Also listed in the catalogue is an ion-exchange model with a transmitter and remote-warning horn ($34.99). This feature is well worth the added price if you have a detector that's some distance from your bedroom, or if you're somewhat hard of hearing.

If you're a landlord, the new law in the District says your detectors must be powered by house current -- not batteries. And these models are hard to find; none of the major stores seem to have them.

Ellenco, a company specializing in smoke detectors and burglar alarms, has an ion-exchange, AC detector selling for around $13 (if you buy a number of units). The company, located at Webster Road and 41st Street in Brentwood, Md., sells photoelectric detectors for around $14 each in quantities.

Montgomery County and Prince George's County residents may not realize it buy they, too, must have smoke detectors in their homes.

All newly constructed residences in Maryland and Virginia must have detectors.