So I need a new Sleeping bag, I'm 195cm so will have to be an XL.

The Mountain Equipment Helium 400 Xl, looks like a good shout, weight pack size and price.

I would go for an Alpkit, if they were a) in stock (ever) b) able to accomodate anyone of a normal size.

Is there anything else that I should consider for the price?

The Alpkit SkyeHigh bags are in stock in large

The sky high is a lot heavier though, although the pack size seems to be quite small.

Do you reckon that it's worth a punt at half the price of the Helium?

I've got the sky high and its great, but its quite bulky and heavy tbh
Really comfortable and warm though

2 different bags really, the ME has 400g of down against 600g of the Alpkit. Both use the same spec down so the Alpkit is bound to be heavier and bulkier as its a warmer bag.

The ME would make for a great 3 season bag if you specifically need the XL size.

The addition of the Skyhigh part, only cam after Jamiep's comment.
I was considering a pipedream, but they are out od stock until late summer.

Anything else I should consider? Length, pack sizer and price are my three major concerns.