As mentioned before, Dueling Network and Devpro are great for looking up cards/archetypes and testing them out. Just pick something that you like to start with.
To save money in the long run, you want to buy staples (if you don't already have them), regardless of what deck you decide to start back up with. Mystical space typhoons, raigeki, dark holes, book of moon, solemn warning, compulsory evacuation device, fiendish chains, torrential tribute, mirror forces, dimensional prisons, pots of duality, effect veilers, maxx "c"s, bottomless trap hole, generic rank 3, 4, 7, and 8 Xyz Monsters, etc.
If you want to take the competitive route, I would strongly recommend researching the upcoming set Clash of Rebellions and picking one of those archetypes to use, then purchase all of the cards necessary to pilot the deck of your choice after doing research online on what those kind of deck lists would probably look like.
The limited/forbidden list is updated every three months (give or take), so be sure to check the main site regularly. YGOrganization.com is a great information resource for upcoming products and such. I usually get my cards & gaming supplies from tcgplayer.com, ebay.com, alterealitygames.com, and coretcg.com
I hope this proves to be helpful.
Ketsui Storm
Another way to go about getting back into the game is by getting the Ritual/Spiritual Beast deck, since everything is very cheap in it. It just came out in The Secret Forces and lots of people are playing it. The most expensive card in the deck is about $5. I'm probably gonna get the whole deck myself and try it out.
Emergency Teleports are $20 each, and you need at least 2.
rolleyes