While you wont be running ancient dual lands, you can build an incredibly effective mana engine for just a few dollars
Craft: Green, Red, and White immediately, Blue and Black later
There are many ways to make a creature big in Modern, and there the 3 Energy can yield many more +1/+1 counters
Some apps will also let you adjust the pricing metric that you use to TCG low or TCG high, or to manually adjust the price point to a number you and your trade partner agree upon
Theres not even as many once-use flicker effects as you probably think
A four-ink card, Mrs Judson, Housekeeper, has some excellent stats one strength and five willpower - for what the card is best used for, which is getting as much additional ink into your inkwell as possible