Kmart offers the Thomas & Friends Take-N-Play Special Collector's Edition Thomas Engine, model no. V7645, for $1.99. Choose in-store pickup to dodge the $5.99 shipping fee. That's $8 under the lowest price we could find for a similar Thomas elsewhere. It's die-cast and comes on a raft.
Of note, Shop Your Way Rewards members will earn a Kmart credit with this purchase and may be eligible for additional credits and discounts.
Note that it should be ready for pickup in four to six days, but there's no guarantee you'll get it by Christmas.