At the time of writing, you can lay 'Wales' at Smarkets in their 'To qualify' market at odds of 2.06.
The standard lay approach gives you a fixed profit of £2.14, or you can underlay for a potential profit of £4.40.
General advice and example for price boosts
Place your bookmaker price boost and lay it at a betting exchange. Use the ‘Qualifying Bet’ setting on the Matched Betting Calculator to calculate your lay stake, which should give you a fixed profit.
If you prefer, you can underlay for a risk-free shot at a larger profit.