There are also many different varieties of sweet lemons out there such as Ujukitsu and Sanbokan. Sweet lemons are acidless/very low in acid and are often described as tasting like lemonade. Some companies sell their variegated pink lemon trees as "pink lemonade trees" because the juice is a faint pink color but is otherwise just as tart as a standard lemon. The meyer lemon is still going to be tart yet not as tart as a standard lemon (with a unique taste as well). If you are looking for a citrus fruit that tastes like lemonade you may want to search for one of the two varieties I initially spoke of. They are pretty easy to find if you google them and I'm pretty sure McKenzie farms in South Carolina sells one if not both varieties.

the so called lemonade tree is no doubt a marketing ploy. It's probably one of the 3 most common varieties, Eureka, Lisbon or Improved Meyer. Pink lemon is a Eureka lemon that has variegated leaves and will be pink when cut open but the juice is not pink, it's just regular ol' lemon juice color, dull yellow.
If you are going to grow it in a container, Meyer is your best bet. for cooking Eureka or Lisbon are both similar in acidity, tartness and sweetness. Pink, while novel, tend not to produce quite as well in most areas.
Ponderosa is a nice lemon, it is huge, so you have to watch your branches so that they don't break, and one piece of fruit is more than you need for most recipes, unless you are making lemonade, which takes a lot of juice. Most nurseries consider Ponderosa a novelty for it's size rather than a producer, although the fruit is good and juicy.

I have a Meyer lemon tree, and a Lemonade tree. They are quite different - the Meyer produces a beautiful-looking deep yellow fruit that is quite tart. The Lemonade produces an uglier, paler fruit that is as sweet as a home-grown orange (so not quite as sweet as a mandarin or a store-bought Californian orange, but certainly sweeter than a Meyer lemon).

They sell Lemonade trees at my local garden centre, but unfortunately for you, I live in New Zealand. I have seen them for sale on an Australian website (http://www.daleysfruit.com.au/fruit%20pages/lemonade.htm), but this isn't the kind of product that can generally be shipped internationally. I have no idea what the scientific name is.

I had(later cut down to add on to the garage) a mature Ujukitsu in the ground and although a novelty and a conversation starter really wasn't a top tier tasting citrus. I topworked it to Minneola tangelo and Nova which are much better. Ujukitsu is earlier than Sanbokan another so called sweet lemon. Uju is ready by Christmas, Sanbokan more like February. My only Uju now is in a 7 gallon pot.

Here is a link that might be useful: mrtexas

Sanbokan is at Woodlanders Nursery. They call it Sanbokan Grapefruit or Citrus sulcata. Google Woodlanders Nursery +Sanbokan. When I tried to find it using their site index the first time I could not. Good luck!
Cath

Forgot to say that I have never bought anything from them and so cannot vouch for them.
Cath

From my research the Lemonade lemon tree is a cross between a lemon & orange (or mandarin orange).