The first one I bought was on a STRICT budget, it is the Trekke 20-60x60mm in Cabela's. They've got it for $150 right now, on sale I think, I bought mine five years ago for that much. Personally, I don't use them a lot, I RARELY take mine hunting anymore (which is why I bought the cheap, lighter one to begin with), I only use them when they're bolted to a stand while bow hunting, or while hunting over LONG ranges where my rifle scope might not reach out and see the longest range there.

Other than for clarity of image, the cost of the higher end ones aren't worth paying IMHO. If you're doing a LOT of shooting and durability might come into play, or you're using it for hunting where it might fog up, then they're worth it. But as far as just seeing what and where you hit goes, you just need something that will let you see it. Cheaper rifle scopes shift zero or have bad parralax, or fog terribly, basically stuff that makes your bullet go somewhere other than where you're looking. With a spotting scope, all you're doing is looking.

I bought a Leup. 20-60x80mm later on, d@mn fine scope, but I wish I would have spent the money on a leup rifle scope instead. I honestly don't think it was worth the money compared to the other cheaper models I've used. It's clearly better than the others, but if all I need is blue jeans, why pay for armani britches?

The bigger the objective, the better usually, since you get a larger FOV. FOV isn't as important for targets as it is for hunting, but it's still handy.

I just bought a BSA from cabelas, 20-60x60mm for $60, can't complain about it, I'm planning on using it as a spotting scope for deer this season, it's light as a feather, and cheap enough that if I drop it in the creek, who cares, but it does what it needs to do.

I'm not saying buy a BSA as your ONLY glass, it IS terribly cheap, and cheaply made, but it gets the job done. I wouldn't recommend it over a Leup., however, I WOULD recommend that you don't spend over $300 on your spotting scope, no matter what you get. A $60 scope might suit your needs just as well as a $600 scope, but I'd recommend a mid-range priced one before I'd tell you to get a high priced one. If you NEED a high priced one, you'd know it (i.e. you'd be a bullseye or BR shooter, or shooting at over 600yrds regularly.)

One thing I did that I'm glad I thought of: I mounted a "sighting scope" to the side of my Leupold spotting scope. It's a little 4x rimfire scope, I got it free with a bb-gun when I was like 10, never got rid of it. I "sighted" the x-hairs for approximately the center of my picture in the other scope at 250yrds, it's not a perfect system, but it really helps speed things along.