Richard,
I think a lot of factors come into play with leaflets. As with anything, I don't think any 1 way of doing it is best. I think it's trial and error, relating to the areas you are delivering in. Up market, down market, whatever! I have tried with and without prices with varying degrees of success. However, if I put prices on them, it is always, without fail - "Prices From".
It gives you that bit of flexibility and a stronger negotiating position. Plus, people have an idea, but are not certain if their carpet/suite fits in with the lowest price on your leaflet. so they may contact you out of curiousity to see if they qualify. You basically cut out the "something for nothing" merchants as well. I usually find they are more of a pain than the top end customer.
The best response I ever had, was from a 4 page full colour leaflet ( A4, double sided & folded ). Delivered to an up market area. Very successful. No prices on these though.
Incidentally, I have just read an article today about direct mail. It was by a professional marketer and it's main principles would probably work for leaflets.
Basically, this is the theory. Target an area in which you are either active, strong or would like to be in. Have the appropriate leaflets designed and printed. Then deliver to your chosen area, whether it be 5,000 10,000 or whatever you need to cover the area. Then 3 months, 6 months and 9 months later you deliver again to that area, but, having made slight adjustments or changes to the leaflet. This would be changes in copy or information, not to your company branding. The idea being that it reinforces your brand upon them and they get used to seeing it and the probability is that when they do need a cleaner, they will use the one that is in the foremost of their mind.
That's the theory and I think it would work well in the better areas ( higher priced jobs ). But it would have to be consistent to get the best results. I must admit, I have been guilty of complacency with leaflets. Doing well, good well paid work flying in and what happens ? Got sloppy with the delivery, stopped delivering and the momentum was lost.
Whilst on the subject of leaflets, I have noticed over the last 12 months or so, a distinct lack of the "Cheapo" leaflets coming through the letterbox.
I would think they are obviously not working now, or they would still be doing them.
Jim G