Cheap tools are like like cheap booze. Better than nothing, in a real emergency, but will give you a serious headache in the morning.
Assuming you are simply doing basic home maintenance on your motorbike you will not need a fistful of tools. Here is is a very good link to the tools needed to carry out day-to-day work on a GS1200. Other bikes, whether BuMW or from Japan, will all be very similar.
http://www.r1200gs.info/misc/toolkit.html
As you will only need a few items, it is better to spend £12 on say two good spanners that you will use for years, than on 15 others that you will not touch once.
There is no need to go crazy. Of course you can buy Snap-On, which will last you a lifetime, either new or via Ebay. But, Halford's 'Professional' range is pretty good for the average home mechanic. It involves going into the dreadful place but worth the trip.
I have a mixture of mid-priced tools and just a few 'top of the range' items for the those that I use most often. These I have bought over the years, so it has not cost me fortune. Keep your new tools clean and tidy (even a cheap plastic tool box will do) with a bit of rag to wipe them down and you will not go too far wrong.