Not a direct answer to your question, this is a copy of an old post of mine.
(1) Self-Contained Celestial Navigation with H.O. 208, ( John S. Letcher, Jr. )
(2) Plastic Sextant: Splurge and get a $150 plastic drum sextant but the $40 cheapest vernier scale will work just fine.
(3) IF you are serious about practice...... then spring for a $100-$200 aircraft bubble sextant and you can practice in your front yard or on the roof of your apt building. Artificial horizons work, but are a royal pain and dramatically limit the sights you can take. Air sextant won't work in bubble mode on the boat unless it is dead calm but there are a few models that have 'horizon mode and can be used for land/air/marine. (e.g. Navy Mark V, // note: parts service avil from Celestaire)
Checking for proper calibration and then adjustment for any sextant errors is a very simple and straight forward procedure and so it not like the errors just creep up one you and leave you stranded. On a stable platfom like an aircraft carrier the $1000 sextant will out perform ( by a mile or two ) the plastic sextant, however on the deck of boat under 100' is much more like an even race.
Look for most any book by 'David Burch' who is the founder of the Starpath navigation school. He is a great writer/navigator/teacher. Particuraly "Emergency Navigation" which really is => most of the possible pathfinding techniquies for the prudent mariner.
The wonderful thing about Letcher's book is (a) he is a very good writer, (2) included EVERYTHING needed to navigate in that book. The sight reduction method HO 208 requires a little bit of math but is VERY compact. Most others such as HO 214, 229, 249 do most all the calculations and you just look things up in tables BUT there are expensive and very very big on the book shelf of a small boat. If you have a 70' schooner then 'no worries mate'. The only thing that is out of date in the book is a 25 year nautical almanac (1975-2000) that was good until 2000. It can be reconstructed from information in Bowitch. Such an almanac is limited to Sun and stars but is cheap and easy to obtain. Not bad to have it all in one book. As of July 7th 2006 there are 7 copies on AMAZON for under $20 and right now two copies are $9.99, you need to add, $3.49 media rate shipping, of course.
Plan on finding out ABOUT where you are rather than the GPS mentality of exactly where you are. About means plus or minus 2 to 10 miles. That works well if you do things like aim for a point to the side of your actual destination. If you hit the coast of ??? after a 800nm passage and you don't recognize anything.....where are you and which way do you head to find it. IF you know you should be a 10-15 miles north then you head south and of course prevailing winds and currents play into your inital choice of a landfall so as to have an easy run to the actual destination. As one gains practice and confidence and if conditions are prime for many good sights then it would make sense to narrow the margin and maybe even have the first sight of land be 'IT".
....... and on and on and on ........ best of luck enjoy!