The link you posted to Halfords is for nuvi 2445LMT, and 90 quid is about 135-140 in US bucks, and i don't consider that to be either a bargain or a rip-off, but i do think you can probably buy better if you look around.

As to the 255/205/200W differences: The 'normal' 2x0W models are very basic navigators, worth about $20 for a 200W, maybe $25-30 for a 260W imo. Your 're-released' 200W is for all purposes a 2x5W except in name, because it has the hw & fw of the hwid 0827 2x5W models which is why you could convert it to 465. Unfortunately you've done it the unsafe way using a straight conversion and not safely as Loly & i suggested.

You say your unit is dead after flashing, but do you mean it won't turn on by the on switch or when connecting to pc, or do you mean it turns on but won't boot? Post full details, if it powers on it might be recoverable.