Not that common as a soldiers pay wouldn't cover that kind of expense.
As has been mentioned the money probably came from someone else.
You need to look at the movements of his Battalion as this may give a reason why. It may be they were due to go overseas & he didn't want to go as overseas postings lasted years rather than months.
Thanks. Just did a Google search for "ist battalion welsh regiment 1889" (yes, I mistyped) and the snippet for the top result (Wikipedia) included "...The 1st Battalion moved to Malta in 1889..."
www.royalwelsh.org.uk/regiment/history-regiment-timeline.htm 1881 The Welch Regiment (third column,near the bottom), click on 'Natal, Egypt, Sudan, Malta'
1st Battalion
1881-1886 Natal
1886-1889 Egypt (1888-9 seeing action)
1889-Dec1893 Malta
1893to Wales, Pembroke Dock
2nd Battalion
1881-1898 Home, Ireland and then moved to India (1892 according to Wikipedia).
So if he was expecting to join the 2nd battalion (Home/Ireland in 1899) then not wanting to go overseas could be the reason
More detail
https://www.maltaramc.com/regmltgar/41st.html on the 1st btn movements in 1889 - 24 Aug 1889 embarked in Egypt, 29 August 1889 disembarked in Malta