£2 for both Regular and Lemon versions in store and online until 31st October.
Normally around £4 everywhere. It's also on offer at Sainsbury's but at £3. Here's the blurb I copied and pasted.
You may think your dishwasher is clean but day after day, limescale and grease build up in its hidden & vital parts: filters, spray-arms and pipes. For flawless results use Finish Dishwasher cleaner with 5x Power Actions. A cleaner dishwasher means cleaner dishes!
*Recommended by renowned dishwasher manufacturers
Use once a month