Well it depends what you are aiming for. Freshwater compared to salt doesn't need as much light, even with most plants. You could get a plastic hex-tank which are fairly cheap at most pet stores. -Pjpets, petsmart, petcetera, etc- Then get a light between 5500k&7700k, about 1-4w/G depending on the plant(s). You can get inexpensive filtration units that are rated for 10g which would keep your 3-5 looking quite nice, but you may have more water-flow then you want.
I'm assuming you want low maintenance, so fish that you can count on only getting so big and with low waste output is prefered. *fewer water changes*
I have even seen a 5-8 gallon hex tank that had a built in light&filtration system in the lid for around 50-80$.
http://www.thatpetplace.com/pet/group/10452/product.web
http://www.thatpetplace.com/pet/cat/...2/category.web
Depending on the plants you want, I suggest you add the decorations and plants long before the fish and give them time to take root or else you will be fighting with the inhabitants to get the plants to survive. Buy some cheap fish *or expensive, but some cheap ones to make sure the tank is ready for more $$ ones*, depending on what you want, many freshwater fish don't need as much room as many saltwater fish do.
Although I may suck at saltwater, but my freshwater tank looks like a gem.