As you might now, the first perk in the Alchemy-tree allows you to make potions and poisons up to 100% stronger. I wonder if making them stronger also improves the value of potions, or if the prices will be the same. Also, if I'm just a 'casual' alchemist (not relying on potions, but just to use some every now and then), is it worth it to invest in Alchemy perks past the first one? Thanks

If your focus is not Alchmey, then like any skill, only take the Perks that you need. How many of those perks you take are up to you.

Now, as you get better at Alchemy, your potions will get stronger and the values will increase. Alchemy potions can be stronger than any in game potion and you can create potions that do things no game potion will. It is a great alternative to Restoration and the Poisons, if you use them, can be quite powerful.

There is a few good perks that you should take. To me I train alchemy but i dont take any perks but the first one, because i am usually putting skill points in other skills more important to my character.

To the question itself, yes, the value of the potions do go up.

I find that Alchemy is one of the skill trees that should not be missed, just like Smithing and Enchanting. One can play the game without them, but these skills do not do anything on their own, but help to improve your main skills. The question is if you'd rather like to specialise or become a multi-talent.

You can maximise the perks for maces, swords and axes in one-handed combat for example, even when you cannot wield three weapons at the same time, and choose to be a specialist in one-handed combat. This is great for role playing.

Alchemy becomes an option when you do not want to specialise like this, but choose your perks only sparsely. You can create very powerful characters with it, or find that it makes the game too easy and that you have to switch the difficulty up.

Do the other perks beyond the first one help? Yes, they do and they will allow you to create even stronger potions.

Not only does the value go up, but since xp is based on value you will level faster if you use alchemy skill increasing pots/enchants.

As mentioned, as you boost alchemy and the potions get stronger, you can sell them for more money. Alchemy is a good souce of income. Just pick flowers and capture butterflies as you travel and you should have quite the supply of ingredients to work with as you return to town.

Aside from being (potentially) rich, you'll have a reliable source of health/stamina/magicka potions and won't have to pay merchants for them and have to settle with what they happen to have in stock.

Yes, taking the perks that improve the strength of potions yields stronger potions, and stronger potions increase value. Not all of the alchemy perlks yield stronger potions. Some make it easier to learn effects, some make it easier to collect ingredients. These of course will not increase strenght of potions and will therefore have no effect on value.

The master perk may actually decrease potion value because potion value is based in part on the number of effects a potion has, regardless of whether the effect is positive or negative. So a potion with a negative side effect may be worth more than the same potion without the negative side effect.

Personally I love alchemy so I perk it for all my characters because without the perks, the potions seem dissapointingly weak. But I only put points into the perks that directly affect the strength of potions (Alchimist, physician and benefacter) so that is only 7 points. If I am playing a character that uses poison I might also perk poisioner.

If I were roleplaying a pure "alchemist" I might put points into the other perks, but they do not seem at all necessary. And the master alchemist perk seems way underpowered compared to the master enchanting perk, so even as someone who loves alchemy (ingredient hunting is fun) I don't have a lot of incentive to spend more than 7 or 8 points in alchemy.