The Beyma that Phil uses costs around £90 from Blue Aran now, although if you order it directly from the UK distributor it's under £70, which is great value. If you want to go lightweight, the neo Faital Pro 12PR320 is similar in performance and costs £128. If you're on a budget, the older version of the Celestion Pulse 12 , the B12-200X (which seems to have an identical specification), is currently selling for £45 at Watford Valves and Lean Business and is definitely a budget "best buy".
If you go for the Faital Pro, you should be able to convert your cab at a later stage to the two-way design currently being finalised in the 12" Cab Diary Continued thread on here.