Don't go cheap. The difference in price is not that much. It's amazing how dehydrated you get riding on even cooler overcast days. The problem is that you don't realize it until you are really affected. Having a hydration pack helps you keep hydrated without making more stops than you'd really like when you're making the miles.

 

I use the Camelback widemouth bottle. It is not a back pack. I mounted it to sissybar or T-bag on my FLHS, and I either strap it on the Tourpack rack or to the dufflebag I carry on the rack. It holds a 100 ounces and I pack it full of ice then fill it with water and it will stay cold for several hours. My wife also has one she uses when she rides with me. I did use a tube extender to allow it to reach up to me from the tourpack. A clip holds it to front of my jacket and I ussaully pull about foot of tube through the clip so I can drink with out unclippping. I get the bite valve inside my fullface helmet with heavy gloves on with no problem. Depending on hot it is I can drink as much as 300 hundred ounces a day, and I typically do a discharge everytime I stop for fuel. Keep your urine light and clear and you will be much safer and will be in much better shape at the end of long day's ride.

 

+1 The camelback got me accross central california in July. Water and ice only. Gatorade at pit stops. No alcohol. Also, if you do not sweat...you've got a problem.