I wouldn't try floodlights. They create waaaay too much heat and don't have the propor spectrum light for aquatic animals and plants. Instead, I would check out local flea markets and swap meets for old equipment. Or even thrift shops have flourescent lighting from time to time for very cheap.
Along the lines of a glass lid, it will be cheaper if you were to save up to get the glass lids available at local fish shops. Ordering pre-cut glass and connecting them with a makeshift hinge winds up being more expensive if you dont already know, or know where to get, exactly what your looking for. For my 55 gallon, I think I paid 25-35 bucks for two glass lids.
Hope this helps.