I'd also like to add my two pennorth.
If you have had a quote for a significant amount (say, over 50 GBP) then I would also ask for more details of exactly what is entailed in the search, where will be searched and how the results will be presented.
I have a lot of dealings with contracts at work and I know how much effort and hassle it can be if things are only agreed verbally. Its amazing how opinions can differ in the space of a couple of weeks.
You might get a funny look or a daft comment, but if the offer is serious, then the researcher won't mind putting together an approximate scope of what he/she will do. It is however entirely up to him HOW he/she will do it and how long he/she needs to do it.
I also run my own translation business, aside of my main job. Every single job I am asked to do, before I start, I send a short note confirming my rates, the time I expect to need, the format of the translation and a final estimate, with the
note that the final cost can be plus or minus 10% of my estimate, to include VAT. I also confirm the date of delivery.
Doesn't take 2 minutes, as I have the pro forma saved in Word. It saves a hell of a lot of hassle when I send my invoice though.
To put it in other terms, you wouldn't buy a PC without knowing exactly what it can do?!?