My first boots lasted over 180,000 miles and 18 years so quality will last.
https://www.fcpeuro.com/products/bmw...kit-3144980005
$70 for OEM quality entire outer joint. I figure for the chance sand got in there and the fact I get a new boot axle spline and axle nut out of the deal it's worth the price.
Also since my inner joint and boot were fine no need to get a knock off full axle.
Full disclosure I have used $120 axles in the past. I would very likely use some highly rated copy cat if I need an inner joint as the OEM full axles are crazy expensive.