Q 53: Is there any source that states that you Enchant Ammunition in bundles?,

cause it seems that it would take forever to make a bundle of +1 Arrows by RAW

From the Magic weapons section of the SRD:
This price is for 50 arrows, crossbow bolts, or sling bullets.
Creating Magic Items

To create magic items, spellcasters use special feats. They invest time, money, and their own personal energy (in the form of experience points) in an item’s creation.

Note that all items have prerequisites in their descriptions. These prerequisites must be met for the item to be created. Most of the time, they take the form of spells that must be known by the item’s creator (although access through another magic item or spellcaster is allowed).

While item creation costs are handled in detail below, note that normally the two primary factors are the caster level of the creator and the level of the spell or spells put into the item. A creator can create an item at a lower caster level than her own, but never lower than the minimum level needed to cast the needed spell. Using metamagic feats, a caster can place spells in items at a higher level than normal.

Magic supplies for items are always half of the base price in gp and 1/25 of the base price in XP. For many items, the market price equals the base price.

Armor, shields, weapons, and items with a value independent of their magically enhanced properties add their item cost to the market price. The item cost does not influence the base price (which determines the cost of magic supplies and the experience point cost), but it does increase the final market price.

In addition, some items cast or replicate spells with costly material components or with XP components. For these items, the market price equals the base price plus an extra price for the spell component costs. Each XP in the component costs adds 5 gp to the market price. The cost to create these items is the magic supplies cost and the base XP cost (both determined by the base price) plus the costs for the components. Descriptions of these items include an entry that gives the total cost of creating the item.

The creator also needs a fairly quiet, comfortable, and well-lit place in which to work. Any place suitable for preparing spells is suitable for making items. Creating an item requires one day per 1,000 gp in the item’s base price, with a minimum of at least one day. Potions are an exception to this rule; they always take just one day to brew. The character must spend the gold and XP at the beginning of the construction process.

The caster works for 8 hours each day. He cannot rush the process by working longer each day. But the days need not be consecutive, and the caster can use the rest of his time as he sees fit.

A character can work on only one item at a time. If a character starts work on a new item, all materials used and XP spent on the under-construction item are wasted.

The secrets of creating artifacts are long lost.
Creating Magic Weapons

To create a magic weapon, a character needs a heat source and some iron, wood, or leatherworking tools. She also needs a supply of materials, the most obvious being the weapon or the pieces of the weapon to be assembled. Only a masterwork weapon can become a magic weapon, and the masterwork cost is added to the total cost to determine final market value. Additional magic supplies costs for the materials are subsumed in the cost for creating the magic weapon—half the base price given on Table: Weapons, according to the weapon’s total effective bonus.

Creating a magic weapon has a special prerequisite: The creator’s caster level must be at least three times the enhancement bonus of the weapon. If an item has both an enhancement bonus and a special ability the higher of the two caster level requirements must be met.

A magic weapon must have at least a +1 enhancement bonus to have any of the abilities listed on Table: Melee Weapon Special Abilities or Table: Ranged Weapon Special Abilities.

If spells are involved in the prerequisites for making the weapon, the creator must have prepared the spells to be cast (or must know the spells, in the case of a sorcerer or bard) but need not provide any material components or focuses the spells require, nor are any XP costs inherent in a prerequisite spell incurred in the creation of the item. The act of working on the weapon triggers the prepared spells, making them unavailable for casting during each day of the weapon’s creation. (That is, those spell slots are expended from his currently prepared spells, just as if they had been cast.)

At the time of creation, the creator must decide if the weapon glows or not as a side-effect of the magic imbued within it. This decision does not affect the price or the creation time, but once the item is finished, the decision is binding.

Creating magic double-headed weapons is treated as creating two weapons when determining cost, time, XP, and special abilities.

Creating some weapons may entail other prerequisites beyond or other than spellcasting. See the individual descriptions for details.

Crafting a magic weapon requires one day for each 1,000 gp value of the base price.