I've rented from these guys before
Rent PAR Meters at Global Aquarium Supply . It was about $50 for the week and well worth it IMO. Take measurements at various points in your tank with your old lights first so you can dial your new lights in to approximately the same level. Then take more measurements as needed so you know how bright you can go and the effect of changing color temp.
As an alternative to renting, I think we could work something out here on the forums that would cost a bit less. The idea was pretty simple and starts when a person purchases a light meter outright, gets their use out of it and then posts it for sale here. Keep one thread going with people on a 'wait list' for the PAR meter and pass it on to the next person at the same cost. In theory nobody pays more than shipping and keeps it as long as they want. If it works out there could be a few meters floating around between members. Paypal would probably be the easiest method of making payments to each other. Just a thought..
