Are you in Illinois? Illinois law permits alcohol purchases at Costco without a membership. (To be more precise, Illinois law prohibits a club membership requirement to buy alcohol). If you go in and say you're only coming to buy alcohol and that's all you go out with, you can buy as much as you like without paying a membership fee.

This is true in some other states as well and is worth looking into, to see if it's legal in your state, if you have a Costco nearby. I don't know how the wine values are at Sam's Club, but the same law applies.

Two. Words. Trader joes. Lots of great wines fairly priced, best return policy in the w
world: if you dont like it bringit back and they will refund your money.

Try Penfolds Kanoonga Hill
https://www.penfolds.com/our-wines/koonunga-hill?lang=

Quite good quality, reasonable prices. Their Cabernet/Shiraz blend is one of my favorite wines. Another is Holy Cross Winery, but it's harder to find outside of Colorado.

i shop a costco in MD. their wines are much higher than competitive retailer shelf price??? by a lot.

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Vinho verde can be delightful. If your wife likes that, have her try albariño, a Spanish varietal that tastes similar (without the slight effervescence), or grüner veltliner, an Austrian one.

My recommendation is to get on mailing lists of solid producers. I don't know really what "budget" means here, but there are some producers with fabulous stuff in the under $20/bottle range.

As a winemaker, I can tell you that reaching a serious budget number (under $10) means either 1) scaling up enormously or 2) manipulating the product. I guess there's always 3) both of the above. Understanding that everyone's different, I would choose to drink less of a higher quality product from a caring producer vs. more of a lower quality product from a conglomerate blending bulk.

For me, budget wines are those for $15 a bottle or less. I find Trader Joe's Grand Reserve wines to be a very good value generally in that range, though their pinot noirs tend to be pretty mediocre IME.

Ditto on the above recommendation for vinho verde; TJ's has it locally for the $6 to $7 range, and it's fine.

Columbia Crest Washington State cabernets, especially their H3 label from Horse Heaven Hills area vineyards, tend to be very good values.

I don't know where you'll find Bandol Rouge in the USA for under $30 except on rare occasion.

You might like various Cahors. Some will fall right within your price range (if you can find them in your location). Some are a bit much, and some seem like they will fit right within your taste profile.

italian table wines are generally quite good value if in italy...