Like most products, wine roughly follows the rule that you get what you pay for. So what if you're on a limited budget?
I was recently asked this question by a friend honest enough to admit that he wasn't too interested in food matching, just something cheap for under NT$400 that was drinkable on its own. I suspect many people think the same way so, whether you just want a glass at home, or are a bar owner looking for something that will work well by the glass, here are some good tips.
Not all wine needs to age; in fact the majority don't improve with time. I've made this point many times, but it is important to remember when choosing cheap wines. Wine ageing is a balance between giving tannins time to soften and secondary bottle-aged flavours time to develop, and not waiting so long that the primary fruit flavours have dried out or disappeared. Most red wines under NT$600 on Taiwan's shelves have not been designed to go through this life cycle. They have been made with softer, riper tannins and don't have the concentration and complexity to benefit from ageing.
For this reason, Tip Number 1 is: Buy them young while they retain all of their fruit flavours. Generally, wines older than three years in this category will be starting to get tired and old. If the producers are not brave enough to put the vintage (year of production) on the label, I usually avoid it like the plague.
Warm, sunny climates can produce softer, rounder styles. I would look towards Chile, Argentina, Australia or South Africa for good, fruity, yet soft, options. Many Italian and French wines have been made for drinking with food and may have higher acidity, tannins or both, and won't be suitable for drinking on their own. You will find some exceptions from Vin de Pays d'Oc in Southern France and some full, yet soft, Primitivo wines from Italy.
For white wines, again, youth is key. If you are lucky enough to find something from New Zealand at this price point, jump at the chance. Otherwise, the countries listed above--with the addition of French wines from the Loire Valley like Torraine Sauvignon, or Cotes de Gascoigne--can be great value when young and fresh.
So look for a vintage on the label, something not more than 2-3 years old and, for a good chance of an easy drinking style, look at something from the "New World" outside of Europe.