A 2 bdrm platinum Westin Kierland Villas (WKV) is the most economical in terms of Maintenance fees. However, I believe the going rate is $12,000-15,000 for such a unit. MFs are ~$1200 for a 2 bdrm (2011).
On the other hand, you can buy TWO Sheraton Vistana Villages (SVV) units in one of the two mandatory sections (Key West or Bella) to get to 148,100 SOs, for a much lower purchase price (no more than $1500 for a platinum 2 bdrm), but your annual MFs will be much higher because you'll have to pay for two. MFs are from $1100-1250 for a 2 bdrm (2011).
SVV Key West and Bella SO assignment
3 bdrm lockoff platinum 125,000-139,700
3 bdrm lockoff gold plus 104,100 - 118,000
2 bdrm lockoff platinum 95,700
2 bdrm lockoff gold plus 81,000
2 bdrm platinum 81,000
2 bdrm gold plus 67,100
1 bdrm premium platinum 51,700
1 bdrm premium gold plus 44,000
1 bdrm platinum 44,000
1 bdrm gold plus 37,000
Westin Kierland Villas
2 bdrm lockoff platinum plus 148,100
2 bdrm lockoff gold plus 81,000
2 bdrm lockoff gold 56,300
1 bdrm premium platinum plus 81,000
1 bdrm premium gold plus 44,000
1 bdrm gold 30,500
1 bdrm platinum plus 67,100
1 bdrm gold plus 37,000
1 bdrm gold 25,800