Optics are a very personal thing. Some folks haven't use a lot of them, and have "target acquisition" issues if the lowest magnification settings are too high. Others (like myself) have had optics on virtually every gun they've ever owned and it's second nature, allowing for higher low end magnification and, consequently, higher high end as well.
That said...
It's hard to argue with your Leupold choice. You don't find many products that are consistently rated that highly, and with almost no really poor ratings.
The "lowest" quality I would recommend would be something in the Bushnell AR/223 realm, roughly $150 and 3-9x. I've used one a bit, and it does fine, if you're interested in saving $100 on your budget.
I have a Minox ZA5 that I really like and their ZL3 can be had for right about $250, in either 3-9x40 or 3.5-10x50. Most Minoz optics are multiple times that price and I find that their "low end" products out perform the price point.
Personally, I like a bit more magnification. I'd be tempted to bump the budget a bit and consider the Vortex Diamondback HP 3-12x42... I don't think I've owned a scope with a max under 12 on anything beside a 22.