First suggestion so hopefully I have the right idea. Credit to FD God who made the last suggestion, whose work I build on here.

From well respected effect tier forum suggestions, we can make an initial, broad range for Soviet Gentleman Terror-Watt relative to Soviet Gentleman with accepted prices. The Electrostatic is 2.8-3 buds and the Roboactive is 4.5-5.5 buds.

-Listed here on the lower rung of the upper tier effects, you can see Electrostatic is mid tiered well below Terror-Watt, while Roboactive is a good margin above it in the upper tier: http://www.tf2pricecheck.net/Thread-GUIDE-Unusual-Effect-Tiers-v%E2%88%9E-Recently-Updated

-Here we find it listed at the top of the medium tier, with Electrostatic near the bottom of the medium tier and Roboactive is at the bottom of the 'God' tier: http://www.tf2pricecheck.net/Thread-GUIDE-TF2-trading-guide-all-you-need-to-know-v1-5-Updated-9-16-13

==> Based upon this, we could accept the upper bound of Electrostatic and the lower bound of Roboactive as a rough initial guess at Terror-Watt's price, so 3-4.5 buds.

First sale was described by FD God ( http://backpack.tf/vote/id/52a3dbb64cd7b8520d8b4575 ): 1 Unusual Bunsen Brave (Smoking effect), 2 Ebenezer (2.8-3 key each), 1 Villain's Veil Strangifier (4 key Strange minus reglar Veil price -> 3.0-3.2 keys), 1 Villain's Veil (5.88-6.88 ref), 1 uncrafable Villain's Veil (4.66-4.77 ref), and 1 ref.

==> 2.5-2.9 bud unusual + 10-11 keys sweeteners = 3-3.5 buds

Second sale was one where I acquired a Terror-Watt after much market research and input from several expert unusual trader friends, which I have since sold for an unpriced unusual ( http://www.tf2outpost.com/trade/16315375 ): 1 Bubbling Brown Bomber and 14 keys.

==> 2.3-2.6 bud unusual + 14 keys = 3-3.3 buds

So, both sales fell within our initial guess range of 3-4.5 buds, and by taking the common low range of 3 and the average high range of 3.4 from the two sales, my final 3-3.4 bud suggestion passes both the common sense test and is satisfying in that the two sales were so similar to one another in terms of price. Thanks for voting and I hope this helps.