I suppose cost depends on where you live. Lighting is the most expensive part of the fresh water aquarium.
I am in Canada. The glass versa-top lid for me is around $50.00, but I have yet to convince my fish store to order it and not charge me the shipping cost lol. If I had it shipped to my door, it would cost between $80 and $100... crazy !! I'm not paying that for a piece of glass.
The light fixture by Current USA, the Nova Extreme would cost me roughly $125.00. Big Al's (in USA) goes for $100.00, on their website.
If you are in the USA, it will cost you much less (even though the Canadian dollar is worth $1.05 American, again.. crazy !!
As far as algae goes, I don't know really. I don't worry about it. Just clean the inside glass if it builds up, or get some livestock that eats algae ?
I think as long as you balance the amount of light with the amount of plants, you can keep it under control.
Good Luck