A good spotting scope is worth its weight in gold, but so is a high-quality pair of binos mounted on a tripod. I finally spent the money to have an adapter stud mounted into my Swaro 10x42 ELs and bought the tripod adapter after sitting behind a buddy's set up a couple of years ago. It made a HUGE difference. I still keep my spotter handy to look even closer if I need to, but if you have a great set of binos, that's something to think about. Most guys out west end up using 15x56s or the new 12x50 Swaros with a tripod.
Back to the spotter question: if you ask 10 people out here, you will get close to a 50/50 answer on angled vs straight eye piece. I prefer the straight eyepiece because leaning over the angled piece hurts my neck after a few minutes. For me, its easier to pan with my eye on the hillside, too. Imagine sitting for hours, which can be the norm, with your head bent down over an angled eye piece. That's my take on it. Everyone is different and some swear up down over the angled eye piece. No matter what brand you get, get a good (best you can afford) tripod. From experience, the cheap ones from Walmart don't work well. They just aren't sturdy enough and the pan heads are neither fluid enough in their movement nor do they lock in place solid enough. You can spend anywhere from $150 to $400+ on a good tripod and then there are the different heads that you need because most tripods are legs only. I have a Slik 330 and love it (under $200 out the door for tripod and solid pan head). A solid window mount is a great idea, too, especially if most of your glassing is going to be from the roads.
I have an older Vortex Nomad 20-60x60 and love it. It was right around $300 when I got it. I didn't want the extra weight of the 80x eyepiece scopes because I carry enough crap far into the areas I hunt, but I know guys that have two 20-60x80 Swaro scopes mounted side by side and hike them deep into Coues country down here! At some point, I will probably upgrade to a higher-end model, but it will likely still be a Vortex. Vortex is great because you get great glass for a decent price and their warranty is tops, but the bottom line is spend the most you can afford on quality glass because that's how you find the animals and it really does help relieve eye-strain.
I see good spotting scopes, tripods, and panheads for sale on coueswhitetail.com and on a local Facebook page called "The Huntin' Store" that is specific to hunting gear for sale state-wide in AZ. If I can help you find anything, let me know.
Hodge-If you read this, AGFD should be hitting credit cards as early as this Friday, so keep an eye on your cc statement!