UK, c.1830s: Palladium Low

The stratospheric price of Palladium had been largely stable in the 20 years since Wollaston's discovery of that noble metal.

1803: 1  Troy  Ounce Palladium  (refined) = £ 24.  (USD$ 109.)

c.1824: 1  Troy  Ounce Palladium  (refined)  ~ £ 25. (USD$ 120.)
 
Citation: The London encyclopaedia: or, Universal dictionary of science ..., Volume 16, edited by Thomas Curtis (1826) p.517

In the 1820s, Palladium was largely unworked, due to its scarcity.  Without access the new Brazilian source, French prices remained higher longer.

c.1835:

On 1833, Johnson's Brazilian supply provided his firm with a wholesale advantage (near monopoly) but glutted the British market.

1835:

In The Correspondence of Michael Faraday: 1832-December  1840, Letter 671, Faraday dismissively cites Mr. Johnson's (wholesale) 1833  price thus: 20/- (20 shillings!)

1833: 1  Troy  Ounce  Palladium  (refined, whols.)  ~ £ 1. (USD$ 4.86) 

1835: 1  Troy  Ounce  Palladium  (refined, retail)  =  £ 2.20   (USD$ 10.67)

A Catastrophic Low Price for Palladium in Pounds Sterling may have occurred around c.1839 (with a 90% Price Drop.)  A higher price in Francs continued abit longer, however.

c.1839: 1  Troy  Ounce  Palladium  (refined, whols.)  = £ 0.70 (USD$ 3.49)

Citation: The Monthly review of dental surgery (1875) p.87

Smee's first edition (1840) did not specify a price point, but his Second Edition offers a "moderately cheap" qualification - the context implies Palladium was less expensive than Platinum. (Subsequent editions retain this statement, then gross misinformation and despite the fact that Palladium became four times more expensive than Platinum.) 

Citation: Elements of electro-metallurgy By Alfred Smee (1843) p.

By the mid-1840s demand again exceeded supply.

1844:

c.1895: an historic low referenced as an aberration, c. 18??