Suitable brand of Skylight window?....

[EzioSuffolk]

Hi,
I need a couple of Pitched Rooflights/Skylights, probably fixed (non-opening), and very approximately 80cm x 100cm.

Velux are the market leader, so presumably rather expensive?
Are there any alternative brands that are of entirely adequate quality, but cheaper? (Ubbink, Whitesales?)
Are there any particular ‘standard sizes’ (around the 80cmx100cm size) that are cheaper, or easier for a builder/roofer to fit?

I don’t need high-end visual design (nothing else in my house is!)

Thanks for advice.