The commemorative wheelbarrow and spade were made to mark the first sod being cut on Llanfyllin Railway in 1861.
The final sale price was £1,100 more than the minimum guide price of £3,000.
The line opened from Llanymynech in 1863 to provide access to limestone quarries and the main line.
Halls auctioneers at Shrewsbury expected interest from specialist collectors as the items were commissioned by Victorian railway engineer Thomas Savin.
In 1857, Mr Savin formed a partnership to build the Vale of Clwyd Railway and became principle contractor for many of the lines that became the Cambrian Railways.
His bankruptcy in 1866 led to the stalling of Aberystwyth and Welsh Coast Railway, which became a part of Cambrian Railways, said Halls fine art director Jeremy Lamond.
"Railway heritage items with this level of provenance always attract great interest from collectors and we were delighted with the price it achieved at auction," said Mr Lamond.
A piece of railway history made to mark the start of work on a Powys rail line 155 years ago has been sold at auction for £4,100.