A business I do marketing for used to use Adwords, the spending was in the region of £1000 per month when I inherited responsibility of the campaign management. My own belief is that it wasn't the right way to market for our type of business (a specific industrial product, with the main customer base being large OEM businesses) so first I filtered the keywords to stop the people just wanting information on the product being made, but then I took a decision last June to turn off the campaign all together, since then there hasn't been a noticeable drop in enquiries... in fact our record month (and the top 3 or 4 months) for enquiries received have been since the AdWords campaign was stopped which makes the saving of £1000 per month even better!
I think AdWords is great when selling to the general consumer market, especially where you can use it to promote a special offer on your product e.g. "The new iPhone 5 for £XX per month" etc. but AdWords isn't for everyone.
Hi there, I would start low, say 200 a month. Really depends on the nature of the campaign and how you want the traffic to be converted. I.e generate leads, collect email addresses or build brand awareness.
I would advise using google conversion tracking, over time you will be able to work out the optimal budget.
I have a load of free 75 vouchers from my marketing practice left over if you haven't applied one to the account already?