Don't aim low.
You have no idea what kind of great deals you might find if you ask around. You might even be able to get yourself a six star like Alexander easier than you could a five star. pool up your four star units you can afford to lose, see how much you could get for them, shop around some more, then get as many pure te as you can get for them, and troll the trade forums looking for bargains.
if you can scrounge up thirty te or so, you can grab a really good five star, even a limited edition one, and it might even be maxed and level broken already.
Alraune has decent stats and her price is godawful low. She's LE, she has decent stats (for her deploy cost) and she's got area attack which is a blast for doing quests faster.
I've seen Adolph and Tugba, Emma, Julia, Joachim, and many others sold at far less than market value. I saw a player looking for Joachim and offering 10 TE worth of TE and goddesses, I saw his offer rejected for not being pure TE, and I located him in game and offered him my fifty-something Joachim for the same stuff instead of the fresh Joachim he was looking to get. Don't lose heart of getting a good trade even if the person you're talking to rejects your offer outright.