Sorry to clarify. Yes, you can buy 500-mile stickers for $30 or you can buy 8 stickers for 35K miles, 16 for 70K, 24 for 105K, or 32 for 140K base miles.

And for the Plat Challenge period, I will be flying 24K base miles, which will get me 12K points (Plat) and 30K base miles (with Gold 25% bonus) and that will get me 12 stickers (4 per every 10) with the 6 base I've already flown this year.

So, spend all my base miles to purchase stickers? or pay fees with miles for individual upgrade, etc..

Also, can you even upgrade on International fares with stickers? I always get N/A on the purchase page...