Once I have a keyword up and running in adwords, I can see how many people searched for that term in the impressions column, but I would like to be able to find search volume before deciding on keywords - do you know of any free or charged services of this type? Hitwise comes to mind but they are beyond my paltry budget. Thanks.
Hi,
It may be awesome but it is not free. Also who is willing to fill all the details required for wordtracker along with cc details. Google Adwords tool is Free, Easy to use, No setup required , relevant data & search volume.
You might also use wordtracker, it’s really awesome for this task. 
Hi
Try Google Adwords free keyword suggestion tool https://adwords.google.com/select/KeywordToolExternal
It shows how competitive the keyword is along with the local & global search volume in numbers. This is will help you initially while selecting keywords.
It will help you for sure
Regards.
market samurai is great but is not free and more expensive