[sirinsidiator]

You could create a slash command in your addon like this for example:

SLASH_COMMANDS["/exportcsf"]=function()
    MyAddonsSaveData = {}
    SHARED_FURNITURE:GetMarketProductCategoryTreeData():GetNumEntriesRecursive(function(entry)
        local line = {}
        line[#line + 1] = tostring(entry.marketProductId)
        line[#line + 1] = entry.formattedName
        line[#line + 1] = entry.icon
        line[#line + 1] = tostring(entry.quality)
        line[#line + 1] = tostring(entry.cost)
        line[#line + 1] = tostring(entry.costAfterDiscount)
        line[#line + 1] = tostring(entry.discountPercent)
        line[#line + 1] = tostring(entry.categoryId)
        line[#line + 1] = tostring(entry.subcategoryId)
        line[#line + 1] = tostring(entry.isFree)
        line[#line + 1] = tostring(entry.isNew)
        line[#line + 1] = tostring(entry.onSale)
        MyAddonsSaveData[#MyAddonsSaveData + 1] = table.concat(line, ";")
    end)
end

It will save each entry in a new line in your saved variables file and you can then just use notepad++ to clean it up and save it as a csv.
You need to open the market tab in the housing editor once before it will produce any data.