I upgraded to first class on Eurostar from London to Brussels for just $12. Here's what I got for my money.

Passengers could choose between a chicken and a vegetarian main.

I opted for the veggie meal – two pieces of falafel, hummus, a slice of courgette, and a quinoa and carrot salad. It tasted delicious, though the portion was small.

The meal also came with a small bread roll, lemon dessert, and bottle of water. I was also offered a choice of drink, and went for a Coke Zero and a cup of tea.

Passengers who opted for wine were offered free top-ups – a major perk of traveling in Standard Premier.

Though an exact comparison isn't possible, if I'd been in Standard class and ordered a sandwich, cold drink, and dessert in a lunch deal from the on-board cafe (like in this photo from a Eurostar journey I took last year), plus a cup of tea, it would have cost me about $15. That's more than the cost of my upgrade to Standard Premier.

To have a single seat for the two-hour journey and get a meal and drinks, the $12 upgrade definitely felt worth it. But I know that I got lucky when I booked.

For most journeys, the upgrade costs at least $25. For some journeys, it's well over $50, and I'm not sure that's worth it for a two-hour journey.