As long as you are fine not running camo, Prana Zions (either one piece or zip off) or Eddie Bauer Guide pants are great pants for your needs without the "hunting brand" cost.
Light, stretchy, durable and dry fast if you get caught in rain.

Sitka early season pant works for me.

My best for this purpose are the Sitka Gear Ascent as mentioned above.

Another vote for nylon fishing pants.  I have three pair that are goodwill or bargain cave tan fishing pants.  They dry very fast even after waist deep in streams or through dew soaked grass.  Easy to spot ticks.  I have one pair with zip off legs.  Two of three pair are difficult for mosquitos to penetrate.

Duluth dry on the fly flex cargo pants... enough said!

I stumbled on some fine lightweight cotton pants.  The discontinued Woolrich tactical elite pants.  If you can find them online, they should be cheap since they were discontinued.  I have them in a coyote brown color.  They are ripstop cotton, very light, very baggy, and plenty long.  I like all of the pockets they have.  These are my favorite for still hunting unless I am dealing with briars (then I want Carhartts).

For treestand hunting, I prefer the zip off fishing pants.  I climb in my stand and take the legs off.  I cannot believe how much cooler I feel basking in the smoke from my Thermacell in shorts.

This year I'm going to get the TusX convert pant. They seem pretty sweet and they zip off into a short!

Sitka ascent pants.  Add a base layer and they are good for cool weather as well.  Expensive but well worth it.

I also look for lighter weight, roomy pant at a reasonable price that can be worn in warmer climates during the summer, as well as during the hunting season. I settled on a pant from Cabela's under the Cabela's Casual's line. This pant is a 70% cotton, 30 % nylon blend. Cost about $50.00 but they do put them on sale. It is probaly considered a outdoor work pant not necessarily a hunting pant.I purchased two pair, one light brown and another green. They wear like iron and are quite comfortable.  The item number inside the pant reads 906397. Hope this helps.

Yep . Fly fishing pants that zip off at the knees. Shirts too.long sleeve . Get them in tan .gray or green

After posting above I went to Cabela's on line catalog. It appears they have changed this pant from 70/30 blend to a 98%/2% blend. Listed as Cabela's comfort outdoor pant. They have limited stock at this time. I havn't seen/tried the new 98/2 blend but the 70/30 blend which I own are quick dry and very comfortable. You might want to read the reviews before making a decision. Good luck with your quest.  

Eddie Bauer First Ascent guide pants are awesome!
I have worn them with a base layer in single digits while winter camping.
I have also worn them in 95degree humid weather.
They don't come in camo, but khaki or olive work well for me!
These pants retail for $80, Eddie Bauer constantly has sales, and I have bought them for $35.

chris <><

I wear shorts under leafy flag pants when its really hot.

Cabelas Microtex light if you want something in camo. they make several weights and the light ones are great for hot weather hunting like early elk season. A lot more affordable than the Sitka, KUIU, FirstLite stuff.

I really like my Kuiu attack pants for warmer to cool weather.  Ken

Wow, lots of big spenders here! The luxury brands are great, but you won't find a better performing pant than Champion C9 Golf Pants from Target. They're normally around $30 but I bought a few pairs for $15. Very light, very tough, and stretchy (which is a huge benefit for hiking). I haven't found one I like better at any price. You won't look as cool, though  

I picked up a pair of mil spec bdu/cargo pants at a pawn shop for $13. They are the lighter in weight and lighter in color ones. I crushed a couple dozen walnuts, added water and soaked the the pants for a couple of days. They are now a good bit darker and a nice dull brown camo. My warm weather hunting clothes I treat with permethrin to solve the tick problem.

I picked up a pair of mil spec bdu/cargo pants at a pawn shop for $13. They are the lighter in weight and lighter in color ones. I crushed a couple dozen walnuts, added water and soaked the the pants for a couple of days. They are now a good bit darker and a nice dull brown camo. My warm weather hunting clothes I treat with permethrin to solve the tick problem.

I'm a fan of military surplus. Tough as nails and cheap as dirt. I think marpat is a great all around pattern. Standard bdu material is light enough for me to get through the warm months.

Military surplus - BDUs, light comfy broke in good -