Sometimes in Neopets the chocolate factory has Red Pteri Tails. They are bought for 1500 and sold for 3000. They are the longest lasting + 1000np item (at the time of writing 26th March 2005).
Do snow faerie quests lower than 4000np for some eventual moola.
If you have a fast computer you can search the wizard for cheap codestones. I got one for 200np.
Play easy games for your style like Turmac Roll and Chia Bomber for active neopians and national neopian for typers. Here is a list of good easy money making games and their payoff.
Web of Vernax 1500np Needs timing, speed and accuracy. Difficulty low. Try to get 1 web on 1st round.