Does anyone know whether you can buy those Tommee Tippee sipper lids on the highstreet? They are clear lids that go on their basic beakers and they have a small round hole in the top. I know you can get them online e.g. from Kiddicare but there's a delivery charge there. I got given one by my HV and they seem fab for teaching babies to drink from an unlidded beaker. Thanks!