It occured to me that a list would be useful...for when you hit the market/speciality shops.
Seeds- buy them in preference to powders.
They are intoxicating when they are fresh ground, and once ground they start deteriorating, so the powder that was ground who knows how long before you buy it, well, it is close to sawdust in comparison.
Curry Powders: Same deal, buy fresh from speciality stores.
I hit an Indian place once every few months and they have spices in containers, I buy it by scooping it into plastic bags and transfer it to little glass canisters with rubber seals, small sizes.
That way it is always fresh when I use it, and go buy more fresh when I run out.
Mortar and pestle.
This is the best tool, it is so useful.
Not only will you be able to grind seeds to powder, you can control the particle size somewhat, great when you want a pepper steak or pastrami seasoning!
It also allows you to bruise herbs and make garlic rosemary EVOO marinades for example, and pound Galangal which is a SE Asian type of ginger that is like wood!
I also have an electric coffee bean grinder dedicated to spices but that is a luxury and useful only if you use a lot of spices.
Mustard seeds -yellow and black
Cardomom seeds Green and Black
True Cinnamon Quills- I buy bulk bags, grind some as needed.
Dried chilies mixed varieties_Asian:Wiri Wiri/Birdseye/Thai long/Chinese very long/Scotch bonnet/Serrena/cayenne/Ghost..and flakes and powders are useful too.
Kaffir lime leaves
Cans coconut milk and coconut cream
Tamarind Juice (in containers these days)
These are the the things I use and always have stocks of, but if you are not bitten by the bug yet, just buy as you need and slowly build up.