OWC Aura Pro 6G + Envoy
To date, OWC is the only SSD vendor offering an aftermarket storage solution for the MBA. Dubbed the Aura Pro, OWC's drive is based on SandForce's second-generation controller and synchronous NAND flash. Architecturally, it's similar to SSDs like OCZ's Vertex 3 and Corsair's Force GT.
The best part is that OWC supplies an entire kit to help simplify the upgrade. A 240 GB package sells for $320, which sounds really pricey to PC enthusiasts growing more accustomed to spending less than $1/GB. However, OWC includes the Torx T5 and pentalobe-compatible drivers needed to access and remove Apple's stock SSD. You also get a USB 3.0-enabled aluminum enclosure called the Envoy, which houses your existing SSD. By creating an external storage device, you're able to repurpose solid-state storage you already paid for. The Envoy's mobility is nice, and we like that nothing goes to waste.