Check this site for very reasonably priced refurbished wheels:

Hubcaps Hubcap Wheelcovers Hub Caps Rims Wheels

I just bought a set for my 4Runner; ~$250/wheel and they look brand new. From the dealer, these wheels were $800 each. Similar pricing on the BMW wheels. Just pick what style you like. IMO, the staggered wheels are the only ones that look right on the X5.

I would take a close look at the entire suspension before putting additional mileage on her. It is not uncommon, especially at that mileage, to need all four front arms, one or both sway bar links, and possibly tie rods. Rear upper arms should be looked at as well. But keep in mind that bad ball joints and other bad suspension parts can compromise the safety of the vehicle, so this should be high on your list. You could easily spend $800 or so on parts alone just on the front end.

Not sure if the brake shudder from you description was the bad suspension components or if the car just needs brakes. If it's a steady vibration, you need brake rotors and pads. If it's just an initial shudder or clunk, I'd be thinking about suspension components bad.

I'd also look underneath and see if you have any oil leaks. They are very common, and there are DIY threads here to address them. A close examination of the whole underside while on a lift is really a must ASAP.

Best of luck with the X5.