This applies to the European context.
For sure the best thing we have to do is to share with each other, and notably within the EU serendipity seed swap, then spread locally, etc. but… Imagine it’s april, you live somewhere in Europe, let’s say in Poland, you just fall in love with this forum and this community, the overall concept of landrace gardening / adaptation agriculture, and and and… the EU serendipity seed swap just arrived in Portugal, and will have to go through Spain, then France, then Croatia, then Belgium, then Germany, then eventually Poland. So you understand that, if you wait for this seed train, for this year, it will be to late for starting your first landrace experiments, your first local adaptations! Because you have no seed, and the last seed swaps in your place were in february… You have a few euros in your pockets. Then you come accross a “low cost grexes for europeans” post on a forum and 15 days later you start landracing carrots, kales, etc…
So while I was searching for a few things using the database, (Framacalc - tableur collaboratif en ligne) I listed very few super value offers to make grexes to start with. Here it goes:
-
Welcome to Croatian Seeds Store (mix)
30seeds of 20 eggplant varieties for 2.50€, or 15 seeds of 15 different tomato varieties for the same price… Apart from those super offer they have loads of watermelon and melon varieties, each for about 2€. I used some of them last year to create separate early grexes of both. Seeds were fine. Fast delivery, serious sellers. -
Blandede Frø Arkiv - Fuglebjerggaard Netbutik Nordic Seed
Mixes of many things, notably kales, tomatoes, cherry tomatoes, faba beans, peppers, leeks, cabbages, winter pepo. … 2.5 to 3€ each mix . (I bought from them for the first time this year) -
Tomate en mélange - Tomate En Mélange à gros fruits | Association Kokopelli
a few mixes at Kokopelli (type in “mélange”) like this mix of 60 seeds of 13 varieties of big tomatoes, for 3.40€ + Franck Morton lettuce’s mix and a few others. I have bought from them a couple of times over the years: quality is OK. Huge catalogue. -
https://www.germinance.com/boutique/semences_potageres_legumes_fruits-tomates_buissonnantes_sans_tuteur_en_melange-article-TPL.awp?pgnIdCategorie=36
Quite a few mixes here, notably this early determniate bush type tomato: 50 seeds of 13 varieties for 3.10€. then 4.50€ for 100 seeds… Or an “early tomato” mix of 11 varieties, mix of 7 zucchinis. Serious seller, selling both to gardeners and market gardeners. -
Recherche | LE BIAU GERME
Type in “assortiment” and you will find different good value mixes, for example about 40 seeds of their 12 sweet peppers for 3.50€. Or eggplants, melons, lettuces, tomatoes and a few others. Serious seller too. -
https://permaseminka.cz/
The only european seed seller doing serious landracing : some recently crossed varieties (moschatas, basil, tomatoes and others), Joseph’s pepo landrace, newly created landraces (peppers), grexes (leeks), etc. To this day I am still unsure they send to EU countries, and you need to use a translator, but it is the only one out of the 193-entries-spreadsheet to offer unstable varieties. So kind of good to start with. -
edit 25/02 : forgot about Nikitovka Seeds in Ukraine: excellent quality, extremely low cost, with quantities twice superior to most others for half or third of the price: link to one of their “mix” pages: different mixes of everything from carrots to watermelon (see this mix of 13 varieties for 1.19€). But… “With the new EU import regulations, we are unable to ship seed to EU member countries.” So if you are european outside of the EU you are fine. US members of this forum can also buy seeds from Nikitovka after some paper work: link here.
You will find mixes also, but less good value, at different stores like semaille.com (Belgium), haalmeeruitjetuin.be (Belgium), deaflora.de (Germany), bobby-seeds.com (Germany), merakiseeds.com (Greece), vreeken.nl (Holland), jansenzaden.nl (Holland), valeyracexotics.com (Hungary), gardenseedsmarket.com (Poland), kcb-samen.ch (Switzerland), etc.
Beware than when a seller says that he says he sells a “collection” or an “assortment”, it is that in one box he puts each individual variety. So you pay for each individually minus 10% or so, which not extremely good value.
You will find loads of other informations in the directory, if willing to find specific species, traits, etc. Carrot mixes are the most frequently sold.
And also you may search for local community seed banks… with free or very good value offers… Like mine: the local group of “Maison de la Semence” (House of the Seeds), specialised in vegetables. Catalogue (french):
CATALOGUE_Thomas Community seed bank Agrobioperigord2020.pdf (2.6 MB)
That would not coast you a penny. Just you will have to follow the community guidelines,. In general you take some seeds and you return some at the end of the season. But it’s been designed for keeping mostly “pure” lines, i.e. not landracing.
Of course, if you have plenty of money you can also buy many varieties individually… if so you can use the directory to find your nearest shop and assemble the grex you want. Then anyway, see you next year for seed swapping 
delicate day today, so that comes a blessing. 
