There are a handful of allowance progressive and allowance peak colts on the new player sales page. These are YEARLINGS so they will not be able to make you money until next sim year, but you'll be able to run them from the very start of their careers if that sounds appealing to you, and the progressive ones have a chance of improving to stakes (gelding can also help them). If you are in your first 20 weeks of game play you won't owe the day rate, but after that it does apply, so please keep that in mind. They are all listed for $100.
From the help section:
MAINTENANCE COSTS
Day Rate - $5 per horse per day, for all horses except foals and pensioned horses. New Players (those in their first 20 weeks of game play) are excluded from paying the day rate. If you own 100 active horses, they will cost you $500 per day.
Board - Board is a weekly charge that is assessed at 12:00 AM Pacific time each Sunday morning. The charge can range from $20 - $200 per horse, depending on which farm or track the horse is at when board is assessed. If a horse is in transit at the time board is assessed, its location (and therefore board rate) is its destination. If a horse is boarded at a player's own farm, then a board fee is not charged. Generally, racetracks have a higher board than farms.