That's not a wise position to take.
I'm surprised you can get that model 480W tagan for £25, but if you can that is the one to go for in your list without a shadow of a doubt. What's an extra 5 or 10 quid?
I've used Tagan PSUs for a number of builds and on the one time I did have a failure it didn't take anything with it. Spending another £10 or so will protect your rig if/when the PSU dies. It's false economy to spend £400+ on a PC then put a cheap PSU in that when it dies destroys your rig and takes your data with it.