If you're looking for a courier to post a chainsaw with then Overland Express might be worth checking out. If you want to have a look at their prices check out their website www.overlandexpress.co.uk for more details. They provide a table on the first page for you to obtain a delivery quote, and I've included a screenshot beneath this reply to show you what it looks like.
In order to get an idea as to how much it might cost you try putting in some random postcodes in the Delivery Postcode box, then enter the dimensions of the package so that you can get a rough idea as to how much it would be likely to cost you. Prices may vary depending upon how far you're posting the item, and whether there are any surcharges for certain areas, but at least it'll give you something to base your research on when trying to work out what to charge for delivery and help you to come to a conclusion as to whether or not it would be worth it.
In the event that you can't make your mind up which courier to use you could list the chainsaw as Collection In Person Only, although if you were to do that it may result in fewer potential buyers, as there may be quite a few people who wouldn't want to have to travel great distances in order to collect a chainsaw when other sellers are providing postage for similar items.
