Jancis Robinson has useful ‘Bargains at Waitrose‘ blog post that mentions some of the more affordable, great wines available from Waitrose:
Whites
A A Badenhorst, The Curator 2022 Coastal Region 13%, South Africa £8.99
Morandé, Terrarum Patrimonial Semillón 2022 Maule 12.5% Chile £9.99
Markus Huber Grüner Veltliner 2022 Traisental 12.5%, Austria £10.99
Zacharias Assyrtiko 2022 Peloponnese 14% Greece £11.99
Reds
The Sardine Submarine 2021 Tejo 12.5%, Portugal £7.99
Los Tontos Sabios 2021 Castilla 13.5%, Spain £8.99
Chateau Oumsiyat, Mijana 2019 Bekaa Valley 13%, Lebanon £8.99
Stellenrust Cinsault 2021 Western Cape 13.5%, South Africa £9.99
Thymiopoulos, Atma Xinomavro 2021 Macedonia 13%, Greece £11.99