A Psalm book was a traditional betrothal gift in the 18th and very early 19th century. They could be stamped with "Med Gud och Dig trolovar jag mig" (With God and Thee I betroth me). Later, in the latter part of the 19th century, Psalm books became a common confirmation gift.
Statistically every household had a Psalm book from the 18th century - one million Psalm books were printed in the 18th century - while only one in ten had a Bible (only one hundred thousand Bibles printed in the same period). The population was less than two million.
Getting a Bible was for a farmer family more of a family decision and investment. It must also be pointed out that not all clergy were happy when a farmer acquired a Bible. It was quite frequently noted in the Household Examination rolls - "har Bibel" (has Bible). Although the reason for the 100 % literacy rate was that it was a basic tenet of the Lutheran faith that everyone should be able to read the Bible themselves (which of course also was the reason for translating it) it was feared that reading the Bible and discussing it with family, friends and neighbours would give rise to "inappropriate" thoughts and questions (and thus question the authorities, i.e. the vicar, a both spiritual and temporal authority). Lay gatherings to study and discuss the Bible (and other spiritual books) were strictly forbidden until 1858/1868 by the Conventicle Act of 1726 (same as in England where, however, it was enacted in 1593/1664/1670 but was abolished already in 1689).
A Bible wasn't usually a wedding gift. Before 1858 it could get you into trouble and after 1858 it rapidly became something most people could well afford to buy themselves.
As always, there was a great difference between social classes. A Psalm book or even a Bible may well have been a confirmation gift if we're talking of someone belonging to the nobility, the clergy or the upper burgher estate. But these people all together only made up something like 2-5 % of the population.
What versions are the Bible and Psalm book you have? The first Bible in Swedish is from 1541 ("Gustav Vasas Bible"); it was revised in 1618 ("Gustaf II Adolfs Bibel") and again in 1703 ("Karl XII:s Bibel"). A complete new translation was published in 1917 ("Gustaf V:s Bibel") and the current Bible is the 2000 one. The first Psalm book is from 1536, the next official one was published first in 1695, then there were new ones in 1819, in 1937 and the current one in 1986.