Compare other token price APIs

Currently we are using coingecko for pricing, which we did because it was the first exchange to meet our needs for price-by-address, when other exchanges were only providing price-by-symbol (which is easy to spoof).

We've had some complaints about price accuracy, so this issue represents the desire to do some research/testing of different price APIs.

AC:
- 3-5 api comparisons.
- Whether they support price lookup by token address (not just symbol)
- Some sense of how accurate their prices are historically.
- Any notes on cost to use, or privacy issues.
- Whether we know anyone there, or have reason to believe we can trust their data disposal practices.

The issue identifies CoinGecko as the current pricing service but names no repository file or test entry point. First locate the existing CoinGecko pricing integration, then compare 3–5 alternatives for address-based lookup, historical accuracy, cost, privacy, and data-disposal trust; document the findings and recommendation.

Written by the indexing model from the issue text.