£12k will buy you a cracking low mileage 2.2 VX - Karl (on this board) just got a lovely example for £11.5k.
Reliablity wise they do seem to be pretty bulletproof so long as you keep an eye on the oil level - i've been on the VX board for 3 years now and any engine issues are few and far between.
A std. 2.2 weighs around 860kgs so it's actually lighter than a 111R - no idea how that compares to a K series car though. VXJON and I have spent many an enjoyable day chasing Elises and Exiges of various vintages and flavours and if we get left behind it's rarely cos the cars aren't quick enough

Likewise those SE'ers who've tried the cars seem to be impressed, maybe even surprised with how nice they are
Robin's comments seem about on the money. A std 2.2 will be fun on the track but it runs 17" wheels all round and as such the fronts are a bespoke Bridgestone.......therefore if you crave 888's or A048's you'll need to change the wheels.
Suspension wise it's almost identical to the S2 (i believe the geo is slightly more understeery) and as such is a good compromise between confort and handling. Contemporary road tests said there was little in it handling wise IIRC.
Jon and I are running S2 exige suspension on the cars (£200 on fleabay) and then Willie at CLCM changed the geo to suit and the difference is amazing. Well recommended.
So in a nutshell you should cos;
- Lower insurance (group 16 for 2.2)
- Bomb proof mechanics
- newer, lower mileage car for less money
- No-one know what it is and everyone comes over to ask
You shouldn't cos
- It's not a lotus, it's a vauxhall (this appears to bother a lot of people)
- You can't get super sticky rubber without considerable expense
- The interior is "wipe clean" and low rent compared to the S2
For what it's worth in Dec '04 i started looking for an S1 / S2 Elise with my budget of £15k and ended up buying a VX. 2.5 years on and 38k later I'd still make the same decison again.
Happy to meet up and show you round the car if required!

Focus ST estate, i3s and more pushbikes than strictly necessary.
....did i ever tell you about the Evora and VX220 i used to own?