Toddler booster seats.

I think Torin is getting a big too big for his highchair - he wants to sit at the table with us, and the tray on his highchair prevents him from sitting flush with the table. As a temporary measure, I've been folding back the tray, as it hangs neatly down the back of the highchair. The result is a true high chair - a chair on long legs - and enables him to sit right up to the table - luckily there's just about enough room for his legs to go underneath. However, it's not entirely safe - if he reaches across the table for something, the chair begins to tip backwards (it's not really designed for this use). I think the time has come for some sort of booster seat, or properly designed toddler seat that will allow him to sit safely and eat from the table. 

I've had a look around (it took a while, as so many products seem to only be available in garishly coloured plastic), and these are some of the chairs I've found:

The AGAM chair from IKEA.

The Handysitt chair, available widely.

The Polar Gear Portable Booster seat.

The Mothercare 2in1 Booster Seat.

The Prince Lionheart booster POD.

I like the look of the IKEA one the most, but I can't help thinking that it still wouldn't be very safe for a 21 month old toddler. The Handysitt is also ok, but quite expensive. At this rate I can imagine us ending up with one of the cheaper plastic ones, and I'd really rather not. 

Any ideas?