Canon 50 1.8 vs 50 1.4

[tremer]

On the suggestion of some folks here I bought a Canon 50 1.8 (about $90). I love the lens and I have used it often in the last year or so. Someone offered me a pretty good deal on a used 50 1.4 and I was wondering if anyone knows enough about these two lenses to give me some advice.

Would it be worth the extra money to upgrade to the 50 1.4? Is the image quality that much nicer?

[Adaptive]

Personally I've never used the 1.8 but I have seen and handled it before.

I love the build quality on the 1.4, it has an alloy case and is lightweight.
The 1.8 build quality feels cheap to me, it's made of plastic.

Again, as far as image quality I don't know because I've never actually used the lens.
But I think if you can find a 1.4 for under $300 go for it!
Then go and sell your 1.8 for $80 or so and you will basically almost have the new lens for free.

Oh and if you are shopping and found this good deal on craigslist BEWARE!!!
DO NOT ship anything, do local transactions only, that place is full of scammers.